Macbook Pro heat issues

13 inch Macbook Pro: Late 2011, 2.4ghz Core i5, 4gb DDR3 1333mhz ram on Lion.

To keep it simple. I load a 1080p Youtube video and the fans go crazy. SMCFanControl reports temps of 90 degrees celcius give or take a few degrees.

I am thinking of lapping my heatsink and re applying the thermal compund.

Has anyone else had this issue and does lapping + reapplying thermal paste actually lower temps enough to warrant doing it?

Thought I would ask here first as Google searches didn't find much to go on...

Thanks in advance!