to watch movies in Firefox, I need tobe in 32-bit mode. How do I get there from here?
I don't think Firefox for Mac has a 64-bit mode. The error message could indicate some other incompatibility... do you want to mention the particular web site?
Have you considered installing a later version of Firefox? 3.5.2 is almost two years old now and has some security vulnerabilities.
If you prefer the last 3.5.x, see:
For the last 3.6.x, see:
On a Mac, Firefox 4 is a 64 bit application.
Not all plugins support 64 bit and if not then you need to start Firefox in 32 bit mode to use that plugin.