Current IS is not optimised for contiguous video. Its too aggressive and sporadic for 25fps or 30fps second after second after second.
If you are shooting video your shutter should be no slower than 1/50th or 1/60th anyway, so the benefit on wide angle lenses is entirely negated. If you are shooting with a standard or tele lens then you should be supporting the camera, or you'll sprain your bicep or back. Agree re: rigs, some are just silly huge and cumbersome.
Fig rig great for run and gun, manfrotto video monopod excellent if travelling light, but 8 times out of 10 I'll be using a tripod with bowl and fluid head. Old habits, and being mindful that shakey footage on 50" plasmas is unwatchable.