Here's a link to George Kalemanis' polafilter FAQ:
http://w3.one.net/~georgek/htmldocs/uvfilter.htm#polq2

And here's a short quote: <<If you use a standard linear polarizer with cameras that use auto-focus and/or auto-exposure, you may have problems. This filter may also cause trouble with manual cameras, if you're using TTL light measurement. >>

Further down he stresses the fact that you may have problems, and thus also may not.

This is the understanding that I had; I believe I've seen and heard similar opinions a number of times. So I was confused to read in this thread that the only difference is the 20 dollars.
Tor

This article relates to photographic apps. Video does'nt require circ polars. Use good (coated) polars, and these are mostly circ polars.