Use real video dimensions

How many times does the interval function get called if you set the *delay* to `0`? I'm curious if this is a "turn of the event loop" issue or something else. Note that `0` is really `4` or `5`, because setInterval implements the [same minimum delay as setTimeout](https://developer.mozilla.org/en-US/docs/Web/API/WindowTimers.setTimeout#Minimum_delay_and_timeout_nesting).