My take is to take the middle ground especially if you'll also be using teh camera for photos as well.
I've had great success with the 32GB Transcend Compact Flash cards. True they're only 133x they are UDMA and I've never had the buffer warning or had any sort of problems. Those cards are only a 100bucks! Thats the good.
The bad with those cards is that 1. they don't transfer fast which sucks when you're in the field making archives. 2. If you're looking to get bang for the buck out of them and double for photos they're not great for burst modes.
I agree with Lance the 45-60MB/sec cards at the moment seem to be the sweet spot - plenty (actually way more then enough) for shooting video, great for still burst mode and fast transfers