Openmax was causing errors and after removal dmesg is clean, but still not able to play.
Disabled SR, increased voltage, decreased DSP freq, but still no success.

Removed DSP files from both my devices and now both can show problematic files without problems with stock DSP. Also SR is enabled, stable low voltage and DSP at 600.

EDIT: Now I'm really puzzled. Reinstalled 720p DSP files again to both devices and no problems with sample files. Still original problematic movie files are unplayable, but new encoded movies are all OK (I did more encoding trials). Don't really know what is wrong with the movies that are not OK. They are too big to upload and I could not edit those so that I could keep original codec setting in the file. Video tools that I have decode and encode files when editing those, so therefore cannot take just a sample from problematic file. Now I use different video tools than earlier and I cannot recall all the settings exactly.

Anyway, there are some differences what comes to playback of standard video formats.

EDIT2: Video file seems to have two video parts inside. Attached more detailed info by MediaInfo tool. Anyway, I think this is not really relevant and therefore it can be disregarded.

Once again, a really much thanks for your support. I appreciate it a lot!