I've been using a 50 ft run. If I have connected to my HD-DVD player it works fine. However when I tried it with my standard DVD player, I noticed sparklies.
Since I wanted to extend the run a bit, I connected the 50 ft cable to a 10ft foot cable, using an "HDMI repeater ampilfier".
Using that combination, the DVD player worked fine, no "sparklies".
So I'm thinking your success may be somewhat dependent on how strong of a signal the source device is sending.