I just found this: Sound x Vision | AVerMedia

Its a new capture card Avermedia makes called "Game Broadcaster HD". Surprisingly it has a VGA input which can be used for either VGA or Component with a breakout cable and it has HDMI input as well. I figured I would mention this since there doesnt seem to be any other vga capture card to capture Dreamcast VGA output on the market. I know most people who have captured Dreamcast in 480p used VGA --> Component adapters to an HD card but this would likely degrade the quality by a small amount because VGA is higher quality than component.

Also, as you might guess from the name it can be used to stream live as well as record and apparently supports a wide range of input resolutions. For $150 seems like a pretty good deal Amazon.com: AVerMedia Game Broadcaster HD Record and Stream PC, Xbox 360, PS3, Wii and iPads - Capture Up To 1080p with HDMI/DVI/VGA/Component Inputs: Computers & Accessories

I will probably be picking one of these up soon.