I had a simular issue with my RPM jumping up and the engine vibrating,just like yours in the video,had no check engine code or lights for awhile,then i was driving fast one time and it finally threw a code,1 cylinder was misfiring.

I went to autozone and bought 1 coil pack for 29.99,the problem went away.

I end up going to my local audi stealership,remembering that there is a recall for our B5's sure enough,the guy said there is a recall on coil packs on my automatic 2001 A4,so he told me to bring it back,later that day at 1:30 PM,waiting in the lounge area for about a hour or so,got me and that was it,i have 4 new coil packs,free of charge. I say go to your local audi stealership and see if your B5 is included in the coil recall,it can't hurt.

here is a video i created,before i got it fixed

http://www.youtube.com/watch?v=4BXTjmCD-Yo

 

Yeah I might as well go see. I really hope their is a recall!