Use OBS studio for recording. It have some great features compared to avermedia software...
1]You can upscale your footage in process of recording. So you can set for example FullHD 1920x1200 resolution and then just reupload to youtube....(options menu)
2]If you pres Ctrl+E, you can crop image from any side - gr8 for removing green bars.
3]Also you can with mouse increase size of image or move it to center/sides to match whole recorded area. But do crop 1st...
4]Many recording formats available....

Some cards in DOS wont show anything because custom refresh rate or resolution not supported by aver. Sometimes can be tricked by running any app in high ress like 640x480, exit it and then switch to low ress....This mean switching vga cable between monitor and card, but sometimes it works....Also running since boot sometimes help....

That sounds perfect. I'll definitely try OBS.

I tried about four different PCI cards for DOS with my 486 board, and none has worked. Only the V3 on the other box. I can still test DOS games from the K6-3+ box, but it would have been nice to test with a more period-correct CPU.

Card don't suppport anything under 640x480. But it works sometime. You just have to make it work in supported resolution and then switch to lower. Then it usually works, but with these screen artefacts, that can be cropped. So best is boot into windows 95, or run some app in 640x480 and once you have card working, then just restart into dos mode, or exit game with 640x480 and start recording your desired game.

Booting on 486 might be problem. Recorded two bios screens from modern board (dual xeons) and both worked fine. On mine P3 board i can see boot fine too. But when i tried to record 286 board bios setup i was unable to do it. I guess that older boards have bios screens in unsupported resolutions or refresh rates. Only chance might be booting to dos with your monitor, run something in higher ress, switch cable to aver a hope that it work....

Thank you, very helpful. I'm away from my computer now, but I will be able to try later this week.

I'm also going to mess around with some upscalers from the DVDO iScan line.

I was able to get the Avermedia to sync with a couple of VGA cards (Geforce 2 GTS AGP & Verite 2100 PCI) by booting into Windows first as suggested, then rebooting into DOS. I didn't use the 486 board but a 440BX board.

The big green bar is still there upon bootup, but then disappears sometimes. It goes away when I run Duke3D at 640x480. When I ran Epic Pinball, it was there for the first menu screen, but it went away after the game started and even stayed away after I exited the game.