@FixingG00D As I replied to your comment on the mod page, Rockstar Editor uses Windows Media Foundation API to encode videos. All I do is to hook media foundation functions and capture the input frame sent to the encoder and encode it myself. The input frame is already decimated from RGB24 to YUV 4:2:0, but other than that there is no data loss in the process.
Yeah each frame takes a bit longer to encode, and when all the frames are rendered in the editor, it takes a couple of seconds to finalize the video. Overall it takes longer, but it's still pretty fast for a lossless encoder.
It is also possible to encode the original RGB24 frames, but that takes much more effort and I don't think it's worth it. The YUV 4:2:0 frames look good enough (in my eyes) for now.