video quality
if preferred video quality isn't available, next best is picked instead.
youtube codec and container
h264: best compatibility, average quality. max quality is 1080p.
av1: best quality and efficiency. supports 8k & HDR.
vp9: same quality as av1, but file is ~2x bigger. supports 4k & HDR.
av1 and vp9 aren't as widely supported as h264. if av1 or vp9 isn't available, h264 is used instead.
youtube hls formats
beta
files download faster and are less prone to errors or getting abruptly cut off. only h264 and vp9 codecs are available in this mode. original audio codec is aac, it's re-encoded for compatibility, audio quality may be slightly worse than the non-HLS counterpart.
this option is experimental, it may go away or change in the future.
twitter/x
GIF conversion is inefficient, converted file may be obnoxiously big and low quality.
tiktok
allows downloading videos in 1080p at cost of compatibility.