I did this little test to help someone at 3D Buzz who was having trouble with mcp…and I just realized something strange…there is no watermark?
I rendered the files as water.$F4.pic >> Houdini Apprentice 5.5.208 wrote them to disk as water.$F4.picnc
then I used mcp to make an avi:
mcp -f 1 300 water.$F4.picnc -o -r 15 -w 640 -h 480 water_01.avi
here is the avi (DivX): link [arctor.com]

and here is a frame from the sequence:
picnc [arctor.com]

if I use mplay to convert them to jpg then I do get a watermark.