You asked
Is the pentax smc da 50 200mm f 4 5 6 ed wr good for video?
The site doesn't rate this lens for video, so I can't tell you it's good or bad for it. What I can tell you is that it's a 50-200mm zoom for APS-C Pentax K bodies, it isn't stabilised, and it frames like a 75-300mm on full frame. That makes it a telephoto lens, and telephoto lenses are hard to hold steady for handheld video.
My video guide favours wide lenses for handheld and vlogging work, and good audio matters more than most people expect.
If you want video from a Pentax K body, the [Pentax smc DA 18-135mm f/3.5-5.6 ED AL [IF] DC WR](/gear/lenses/pentax-smc-da-18-135mm-f-3-5-5-6-ed-al-if-dc-wr/) starts much wider, so it's the more versatile starting point. Its page has no further specs yet, so check the details before you buy.
Written by Claude from this site's pages.