The size limit for initial load is 40k but if you need to load larger files you may use the polite load component.
The initial masthead load can't exceed 50k and all mastheads should use polite loader.
rich media will add more weight to the page when is loading for that
reason weight restrictions are needed. When polite loader is used the
rich media creative will wait until the page is loaded to load.
The way you use a polite is creating a parent file that will load a child or the creative you want, this file with the polite should only have the polite loader and the Enabler, if you do it like this the second load, the child file can be bigger Polite Load SWFs + video can't exceed a total of 1MB
For more information about best practices, polite load and weights please follow next links: