It's a technical thing, not a legal one. The current client is blindly, stupidly tied to the Ubuntu 32 bit distribution in ways that are dumb even for a binary package on Ubuntu.

I'm running the Steam client on 64-bit Ubuntu 12.10, and didn't do anything special to get it installed. Why do you say that it's tied to the 32-bit version of Ubuntu?

Do the videos work? Did you follow the 'special' instructions to install the 'special' version of Flash that will work with Steam? Because I sure didn't, and so no videos in the Steam client play. Though that's probably even worse than being 32-bit specific.

In fairness, steam videos don't work for me even in Windows. Something about wrong flash version. I really wish they would just embed a normal video player.

I dunno. The videos don't even work on my Windows machine, as I don't have Flash installed over there. If I wanna see promotional videos, I run on over to Youtube.