How to send a large MMS for free from a PC?

Question

I have a Samsung Gt-B2100i and there is a limit on the MMS size from the OS which is equal to 300ko. I can send 50 Mo with my Mobile network operator.
I often send videos to peoples without internet (but use the Mobile network operator), but I can't send them with my phone since they are usually 2 Mb large (most of the time).

So is there a free on-line service or a software which I can use to send MMS to a French mobile phone?

Note for software : I'm already using my phone to get internet over bluetooth on my PC. There should be a similar software for sending MMS. I don't care about the OS as I can use OSX linux or windows.