-As far as the game you listed it seems fine.
-For HD video editting, you might have some small issues with the 650, its not a workhorse GPU.
-Watching HD movies, you would be-able to watch 1080p, it would just scale down to your resolution of 1600x900.
-Multitasking shouldn't be a problem.
Other than the 1600x900 resolution, the laptop seems fine for your needs.