My train of thought was that he's uploading to youtube, which allows only for lossy compression up to a certain bitrate anyway. If you know the quirks of reencoding and are able to supply YouTube with a higher quality source, and you don't mind the extra time it'll take, go for it. I agree that KEGA's recording format produces higher quality videos for a lower bitrate, and people don't generally distribute this source file. I'm curious if there will be any visible difference on YouTube. P.S. the part where he uploads to YT is purely a speculation on my end.
Well, my train of thought is that if you're going to bother doing any editing, you'll want as lossless a copy as possible to edit first. If you're just gonna dump whatever onto YouTube without editing, then sure, just use ShadowPlay.
The quality is virtually the same as recording the emulator directly in Shadowplay(but you forgot at the time or that wasnt an option). You get to keep the original lossless file. Its the fastest reencoding out there. Like we discussed with Shadow Hog, this is for people who are not very good with reencoding or don't have the time. If you upload the Kega file directly to youtube, the quality loss is humongous. Not everybody is a wizard(hint, hint, FF XIII FMVs )
There's better ways to process KEGA video, but I don't think anyone here wants to fuss about with AviSynth...