I agree with Fishyfishy also. The photos all look normal to me. Not quite sure what you meant by white color showing up underneath scales. One of mine looks just like that when I shined a flashlight on his head (during my examination of his scales which he had scraped one off the decor - to make sure no infection was occurring). If I just look at him with my naked eyes without extra light, I would say his head is quite dark, but with light, I know it's more grayish (whereas my other one is really dark black even with extra light). So I would say may be that's just his normal coloring. From the video, he looks quite active and inquisitive to me, a good sign of a healthy fish. I suggest just continue to monitor him (hehe...like you don't already), if he is active and loves to eat, he is probably ok and loving his good home!
Good luck and happy betta keeping!