Why dont space probes send back live videos from say Mars or Venus?

i believe they do but they very grainy.i did this thing about sun spots it was in real time as light travels that it thousands of us did it. It was to try and guessermate solor activity and how it effects us.some years ago this activity knocked canada out caused many problems...i think the site is astronomy zoo run by royal obseverory in uk,nasa prob got something similar.i wish i could remember full web address.black and white pics very grainy and jerky