The only thing (button or otherwise) that's similar to what you talk about would potentially show up on the right-most part of the screen (Above, or around the Buy Tokens graph with token amounts and prices). This again can be put there by offer providers. There is no programmed watch-videos-for-tokens button placed anywhere on the screen, be it in-game interface or the sidelines like in the Web version. If this button is no longer there, then the provider who supplied it for some users no longer does this service.