couls also be the fps. web is usually around 15 tv / movies are 30. if you have the time, try rendering at 60 fps. view it. no flicker? remove every other frame. view flicker? from original 60 fps remove every 3rd frame. view it often helps to see more detail with higher frame settings. you can see where the flicker is moving. it could be a minute difference in light positioning between some frames. though the flicker beside the nose is more suggestive on render calculation issues.