You need to get the HLS m3u8 playlist files from the video's manifest. There are ways to do this by hand, but for simplicity I'll be using the youtube-dl tool to get this information. I'll be using this live stream as an example: https://www.youtube.com/watch?v=_Gtc-GtLlTk
First, get the formats of the video:
? ~ youtube-dl --list-formats https://www.youtube.com/watch?v=_Gtc-GtLlTk
[youtube] _Gtc-GtLlTk: Downloading webpage
[youtube] _Gtc-GtLlTk: Downloading video info webpage
[youtube] Downloading multifeed video (_Gtc-GtLlTk, aflWCT1tYL0) - add --no-playlist to just download video _Gtc-GtLlTk
[download] Downloading playlist: Southwest Florida Eagle Cam
[youtube] playlist Southwest Florida Eagle Cam: Collected 2 video ids (downloading 2 of them)
[download] Downloading video 1 of 2
[youtube] _Gtc-GtLlTk: Downloading webpage
[youtube] _Gtc-GtLlTk: Downloading video info webpage
[youtube] _Gtc-GtLlTk: Extracting video information
[youtube] _Gtc-GtLlTk: Downloading formats manifest
[youtube] _Gtc-GtLlTk: Downloading DASH manifest
[info] Available formats for _Gtc-GtLlTk:
format code extension resolution note
140 m4a audio only DASH audio 144k , m4a_dash container, mp4a.40.2@128k (48000Hz)
160 mp4 256x144 DASH video 124k , avc1.42c00b, 30fps, video only
133 mp4 426x240 DASH video 258k , avc1.4d4015, 30fps, video only
134 mp4 640x360 DASH video 646k , avc1.4d401e, 30fps, video only
135 mp4 854x480 DASH video 1171k , avc1.4d401f, 30fps, video only
136 mp4 1280x720 DASH video 2326k , avc1.4d401f, 30fps, video only
137 mp4 1920x1080 DASH video 4347k , avc1.640028, 30fps, video only
151 mp4 72p HLS , h264, aac @ 24k
132 mp4 240p HLS , h264, aac @ 48k
92 mp4 240p HLS , h264, aac @ 48k
93 mp4 360p HLS , h264, aac @128k
94 mp4 480p HLS , h264, aac @128k
95 mp4 720p HLS , h264, aac @256k
96 mp4 1080p HLS , h264, aac @256k (best)
[download] Downloading video 2 of 2
[youtube] aflWCT1tYL0: Downloading webpage
[youtube] aflWCT1tYL0: Downloading video info webpage
[youtube] aflWCT1tYL0: Extracting video information
[youtube] aflWCT1tYL0: Downloading formats manifest
[youtube] aflWCT1tYL0: Downloading DASH manifest
[info] Available formats for aflWCT1tYL0:
format code extension resolution note
140 m4a audio only DASH audio 144k , m4a_dash container, mp4a.40.2@128k (48000Hz)
160 mp4 256x144 DASH video 124k , avc1.42c00b, 30fps, video only
133 mp4 426x240 DASH video 258k , avc1.4d4015, 30fps, video only
134 mp4 640x360 DASH video 646k , avc1.4d401e, 30fps, video only
135 mp4 854x480 DASH video 1171k , avc1.4d401f, 30fps, video only
136 mp4 1280x720 DASH video 2326k , avc1.4d401f, 30fps, video only
151 mp4 72p HLS , h264, aac @ 24k
132 mp4 240p HLS , h264, aac @ 48k
92 mp4 240p HLS , h264, aac @ 48k
93 mp4 360p HLS , h264, aac @128k
94 mp4 480p HLS , h264, aac @128k
95 mp4 720p HLS , h264, aac @256k (best)
[download] Finished downloading playlist: Southwest Florida Eagle Cam
In this case, there are two videos because the live stream contains two cameras. From here, we need to get the HLS URL for a specific stream. Use -f to pass in the format you would like to watch, and -g to get that stream's URL:
? ~ youtube-dl -f 95 -g https://www.youtube.com/watch?v=_Gtc-GtLlTk
https://manifest.googlevideo.com/api/manifest/hls_playlist/id/_Gtc-GtLlTk.2/itag/95/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/cmbypass/yes/gir/yes/dg_shard/X0d0Yy1HdExsVGsuMg.95/hls_chunk_host/r1---sn-ab5l6ne6.googlevideo.com/playlist_type/LIVE/gcr/us/pmbypass/yes/mm/32/mn/sn-ab5l6ne6/ms/lv/mv/m/pl/20/dover/3/sver/3/fexp/9408495,9410706,9416126,9418581,9420452,9422596,9422780,9423059,9423661,9423662,9425349,9425959,9426661,9426720,9427325,9428422,9429306/upn/xmL7zNht848/mt/1456412649/ip/64.125.177.124/ipbits/0/expire/1456434315/sparams/ip,ipbits,expire,id,itag,source,requiressl,ratebypass,live,cmbypass,gir,dg_shard,hls_chunk_host,playlist_type,gcr,pmbypass,mm,mn,ms,mv,pl/signature/7E48A727654105FF82E158154FCBA7569D52521B.1FA117183C664F00B7508DDB81274644F520C27F/key/dg_yt0/playlist/index.m3u8
https://manifest.googlevideo.com/api/manifest/hls_playlist/id/aflWCT1tYL0.2/itag/95/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/cmbypass/yes/gir/yes/dg_shard/YWZsV0NUMXRZTDAuMg.95/hls_chunk_host/r13---sn-ab5l6n7y.googlevideo.com/pmbypass/yes/playlist_type/LIVE/gcr/us/mm/32/mn/sn-ab5l6n7y/ms/lv/mv/m/pl/20/dover/3/sver/3/upn/vdBkD9lrq8Q/fexp/9408495,9410706,9416126,9418581,9420452,9422596,9422780,9423059,9423661,9423662,9425349,9425959,9426661,9426720,9427325,9428422,9429306/mt/1456412649/ip/64.125.177.124/ipbits/0/expire/1456434316/sparams/ip,ipbits,expire,id,itag,source,requiressl,ratebypass,live,cmbypass,gir,dg_shard,hls_chunk_host,pmbypass,playlist_type,gcr,mm,mn,ms,mv,pl/signature/4E83CD2DB23C2331CE349CE9AFE806C8293A01ED.880FD2E253FAC8FA56FAA304C78BD1D62F9D22B4/key/dg_yt0/playlist/index.m3u8
These are your HLS m3u8 playlists, one for each camera associated with the live stream.
Without youtube-dl, your flow might look like this:
Take your video id and make a GET request to the get_video_info endpoint:
HTTP GET: https://www.youtube.com/get_video_info?&video_id=_Gtc-GtLlTk&el=info&ps=default&eurl=&gl=US&hl=en
In the response, the hlsvp value will be the link to the m3u8 HLS playlist:
https://manifest.googlevideo.com/api/manifest/hls_variant/maudio/1/ipbits/0/key/yt6/ip/64.125.177.124/gcr/us/source/yt_live_broadcast/upn/BYS1YGuQtYI/id/_Gtc-GtLlTk.2/fexp/9416126%2C9416984%2C9417367%2C9420452%2C9422596%2C9423039%2C9423661%2C9423662%2C9423923%2C9425346%2C9427672%2C9428946%2C9429162/sparams/gcr%2Cid%2Cip%2Cipbits%2Citag%2Cmaudio%2Cplaylist_type%2Cpmbypass%2Csource%2Cexpire/sver/3/expire/1456449859/pmbypass/yes/playlist_type/LIVE/itag/0/signature/1E6874232CCAC397B601051699A03DC5A32F66D9.1CABCD9BFC87A2A886A29B86CF877077DD1AEEAA/file/index.m3u8
