Social Media Marketing

Such as apps.. ? I know Twitter has that mobile device thing where you put your phone number and receive updates. But I want a way to easily access onto Twitter on my phone. Are there only certain types of phones that can do that?

I am searching desperately for months now to find a simple way to download videos from facebook to my computer but nothing has worked for me so far.Could anyone give me a piece of advice on how to do that?Thank you!