hmm... I posted a capture driver but not tried it. It was for Linux.
With that you could use vlc but I dont know if the unix version has a gui.. so might be a pain to mess around with.
VirtualDub is also a good program, I dont know if there's a Linux version.
I dont have a problem recording openGL on windows, but I usually turn on r_ignorehwgamma so what you record is what you see
On windows there is a great program called Fraps www.fraps.com/,
it performs really well and you there is not much noticable performance when recording and playing at the same time. It runs in the background and as soon as you open an openGL program you hit F9 once to start and stop it recording. It has it's own Divx codec so doesnt use much space. So I'm sure if windows can do it, then Linux can too
But what Jack says makes sense, in some instances you would just see the desktop, but Im sure there are options to switch it.
I have a tuner card but not really had any use or problems with software drivers which are recognised as hardware. It might give you better performance and if you wanna watch tv it maybe worth the money
Is it necessary to record in openGL? I didnt think there was much difference when playing demo's so turn it off and i get much better performance.