I've heard the Pentax 50mm primes are good for video in terms of speed, breathing, and focusing. Can the K style mount lenses be adapted to the 7D? I'm unclear on which Pentax lenses can be adapted to Canon 7D's.

btw, I did try googling, here's a sampling of the kind of thing I got of various types of Pentax lens mounts.
PK
KF mount
KA mount
KAF mount
KAF2 mount
KA2 mount
"Crippled" KAF mount
"Crippled" KAF2 mount
R-K mount

The professional range of 35mm Pentax lenses are superb, and my favourites are the A* lenses.

I have adapted a couple of Pentax K lenses to my 5D, and believe you should be able to do the same for your 7D. I bought adapters for around $24 each on line. On one of the lens. You may need to do some minor surgery to remove protruding levers, that are actuated in certain modes on your K camera, but the loss does not interrupt the capabilities using it with my 5D.

Can Pentax SMCP-FA 50mm f/1.4 work with the 5DMK2 and 7D?