mark as-live streams as such

[garret1317]

arg implemented
most of the timefree formats arent actually downloadable though, because they're streamed to you as live
so we need ffmpeg

probably need to have a list of whats compatible with what, a la yt-dlp's extractor

Originally posted by @garret1317 in #17 (comment)

[garret1317]

to clarify:
for timefree we specify the live status as was_live
so the streams get downloaded with yt-dlp's native hls downloader, and not ffmpeg
because oh theyre not live, we dont need ffmpeg for this
yt-dlp's downloader doesnt work with live hls, so it ends up only downloading 3 fragments

need a way for as-live streams to use ffmpeg, and not-live streams to keep using the native downloader