wow, trying to cover up something on moving fabric... could be hard to pull off seamlessly (so to speak)
but you never know, you could be lucky.
basic premise is you duplicate the clip on top of itself (hold Option + Shift and drag it upwards)
cut a hole in the top layer where the logo is using the 4 or 8 point garbage mattes (i recommend the free-to-download Paul Crisp Garbage Mattes)
and keyframe that to track with the logo.
you'd then off-set the lower layer so that the hole is filled with a logo-free part of the fabric.
Sending the clip to Motion would give you better tools. including a MUCH better way of drawing around the logo,
PLUS tracking tools so you wouldn't have to manually track the matte.
nick