well i tried with default windows phone camera and dont have it. but with Nokia Camera i get this white pixel (when in video mode). software bug or my display problem?
strange , try to do a soft reset , by holding volume down + lock button until your phone vibrates and restart itself , ignore slide to power warning on your phone
well before this i send my device to Nokia Centre an asked them to format and after get it back the problem still there. but weird is it only happen in nokia camera if i tried pixel checker app the problem are not visible. hmm
you should take your device to the nearest nokia care centre , they will diagnose your Lumia 1520 for this issue and if they found this faulty , they will repair\replace it for you , Good luck !