If you have a fairly recent Nvidia GPU (starting from Geforce series 6xx), are running Windows and have installed the actually-it's-great-not-to-check-for-drivers-once-in-a-while Geforce Experience software, you may have noticed that they have added the "Shadowplay" functionality for quite some time now. I was wondering if it was working with MAME and... it does ! I think it's quite good: It gives you an already compressed, 1080p, 60 FPS file (h.264, this 3:38 footage weights 376 M and since it's using the GPU hardware encoder, there's no (I haven't felt any anyways) additional lag whatsoever contrary to some other more traditional screen recorder. There's some drawback though: You have to play fullscreen You have to keep some 5-ish GB free in your hard-drive (less if you use the medium or low quality setting) Doesn't work with older Nvidia GPU Issue 3 I don't care, issue 2 is sort-of a non-issue since storage is cheap nowadays, issue 1 is a tad more problematic if you'd like to keep an eye on IRC or twitch or youtube or whatever while you are playing (why would you do that ?).
Re: FIY: Nvidia's Shadowplay (always-on recording) is actually quite serviceable for That's cool. Good to know! In the past I've used Fraps, but I doubt it uses the GPU.