The main issue with video on the chumby-branded devices is that they're simply not powerful to play anything but most trivial video. You'd need to encode it in FLV at 320x240 at a relatively low frame rate. Youtube *used* to host in this format back in 2006-2008 but no longer does so.
The Sony dash, on the other hand, uses a processor that it typically used in a TV set, so it does have the power to play video in a variety of formats.
The issue then is: "what video"?
The commercial video services like Netflix, Amazon Prime, Vudu, etc all require formal licenses and to be paid, on top of the costs of development and certification. They all also require that the device be made closed and tamper proof, which is by definition no longer the case with the patch that turns them into chumbys. Youtube has closed their APIs so they're not an option any more.
That pretty much leaves public domain video - the media player on the dash can play them. So, at that point somebody needs track down that video (archive.org is a good source) and to write the wrapper software to play it. Unfortunately, at the moment, despite the general openness of the devices and the availability of documentation and tools, for some reason that someone is generally always expected to be me.
Unfortunately, I'm currently completely slammed by my day job. I'm not even at home at the moment, I'm typing this from a hotel room in NYC, where I will be off and on for the next couple of weeks. Right now, I'm just hoping I'll get some sort of breather at Xmas.