I had the same issue back in the summer when I first added Kodi to my Pi, but I can’t remember what it was that I changed… It might have been changing the memory split… I not sure what I am currently using, but it’s around 320. Go into the pi settings and set gpu_mem=320… You might not be giving the gpu enough ram. I really wish I could remember what it was that I did to fix it, but I had that issue back in July and I simply can’t remember for the life of me what it was nor off the top of my head anything else to try.
If your running Kodi on Pi, you should give the GPU around 320 mb of memory anyway, as it needs it to properly run, hopefully that might fix your video issues as well.