That camera shoots video in the MJPEG codec -- a surprisingly primitive codec for such a high-level camera and one that Premiere Elements unfortunately doesn't support. This is complicated by the fact that the camera also shoots in 1080p, a frame rate Premiere Elements doesn't support.
I'm not sure what video editing program to recommend to you. Premiere Elements is definitely not it though. If the camera comes with a video editing program, then that's definitely what you should edit this very unusual format with.
You may also find some support in Windows MovieMaker or iMovie, depending on which operating system you're using.
If you have the camera's utility disc, then their flavor of MJPEG should be on that disc. It might be a separate install, might get installed with the driver for the camera, or, more likely, get installed with Pentax editing/cataloging software.
Once properly installed, PrE might, or might not, be able to edit the footage. Not all CODEC's can be used by all NLE's, so it will depend.
I would install the Pentax MJPEG CODEC, and test the files in PrE.
Using Google and entering - convert mjpeg avi
I have NOT used either program, so read and decide
While I do not see a lot of MJPEG, I have edited it smoothly, and natively, with the Nikon (in my case) MJPEG CODEC installed. Conversion might not be necessary, if you have installed the Pentax MJPEG CODEC. I do not know about the Pentax MJPEG CODEC, specifically, so it might just be perfect, or it might not work. If it's the latter, then see this ARTICLE, however, as camera mfgrs. tweak CODEC's for their cameras, it is always best to use their version of any CODEC.
I also got this problem, try to fix it with k-lite codec pack -without success, than I remember that during installation was note about insatalling QuickTime, I install it and voilà! - I load my video.
(K-5, Win7x64, PE10x64)
Europe, Middle East and Africa