+1 for 50 1.8 using manual focus
Id use a cheaper prime with manual focus. For something wider but a lil more expensive, the samyang 14mm 2.8 is great for video. There is also a slightly more expensive "cine" version of the samyang with a manual aperature adjustment ring. You can de-click the aperture ring to smoothly adjust aperture without abrupt exposure change while filming
for zoom, the 24-105 is a great choice with IS... although I'm not sure Id trust that one in the hands of a clumsy holder LOL. Lok from digitalrevTV on youtube uses a 24-105 on a 5DII hand-holding and it always looks very pro.
-1 for 50 1.8
Utterly horrible to manually focus with its tiny mf ring with minimal travel. Makes accurately focussing damn hard, especially with fast moving subjects (like kids unless they're asleep)
If you go down the prime route you would be way way better off using an old prime which was designed to be manually focussed with an adapter. Or if you can find a cheap copy the tokina 35mm f2.8 macro is a very nice lens to mf with which is reasonably cheap and gives you a standardish focal length (50mm on crop is great for close ups, but particularly indoors where distances tend to be limited it is nowhere near wide enough for gv's)
Cheap but good zoom for video look for the tamron 17-50 f2.8. Without VC is sharper, with VC will probably give you better results handheld though.