What do video sender atchualy do?

we have virgin downstairs and i was wondering if i brought a video sender and put it in my room would i be able to get virgin on my tv and could i watch 1 program and my mum watch a different 1 downstairs or would we both have to watch the same program .... and if we can watch seperate channels is there a controler i have to get .. p.s the 1 i was looking at buying was a href="http://www.argos.co.uk/static/Product/partNumber/5347926/c_1/1|category_root|Home+entertainment+and+sat+nav|14419512/c_2/2|cat_14419512|Television+and+audio+accessories|14419521/c_3/3|cat_14419521|TV+and+video+senders|14419542.htm" rel="nofollow"http://www.argos.co.uk/static/Product/pa…/a