How fast can video/ transmission waves travel through space? Something that has been on my mind for quite a while now and has sprouted lots of thought, is whether we can create a machine to put into space, far away from the earth, and use it to see back in time. I'll explain this a little more:
Say that a VERY large telescope, able to magnify images at extremely extensive magnifications, were to be sent out into space and placed in orbit around the earth about ten light years away; and used for the purpose of, starting from the time that it reaches its destination, seeing the light coming from the earth, which would have been from ten years earlier as the light is still travelling and is only reaching this point in space after ten years of it actually happening.
Now it is all well and good for the telescope to see these images of the earth back in the past; images of very high quality I am talking about, able to see humans walking around in a street quality, but if it were then to send these images back to earth, how long would it take for the message to send/ travel to the receiver on earth? Also, is it even possible to send and receive information from so far away? 
If the machine were to be used for forensic purposes, like rewinding the clock to see what happened live in a murder after it had happened, up to ten years after in fact, the pictures would need to be sent and received very quickly so that the time to receive the photos wouldn't be so long that the person convicted of the murder could no longer be held against their will without the evidence.
I hope there is enough of an explanation here to get minds working. 
 A: Even if faster than light travel were possible you would have to travel millions (total guess) of times faster than the speed of light just to catch up with that light that was emitted from Earth so long ago. The funny thing is, we can do it to other worlds.
A: Your idea is theoretically possible. Answering the question's title, it depends on what kind of wave you use to transmit video information. I'll assume electromagnetic waves (e.g. radio wave, microwave, etc.). I can't say what frequency (and hence type) of electromagnetic wave is ideal for the job, as there are several factors to consider and calculate, atmospheric transmittance for one. An electromagnetic carrier wave means that your information travels at light speed. The near-vacuum interstellar medium (outside the solar system) and interplanetary medium (outside the planets), as well as the Earth's atmosphere is pretty sparse that any EM wave can travel near $c$. However, information from 10 light-years away will still take 10 years to reach Earth. That means graphical information will have a round-trip time of 20 years, coming from Earth and back again.
Now about whether it is possible to send signal from so far away, I can't be sure, but focusing waves of certain frequencies may help. Generally short-wavelength waves are less diffractive and can stay focused for a longer distance, but these waves will have trouble getting through the atmosphere. You can of course put another satellite near Earth to transcode the wave to radio wave and then forward that back to Earth. SETI uses radio waves in attempts to contact aliens though, so radio wave might be good enough after all.
As an alternative to your idea, why not just use a satellite close to Earth and store the data in digital data storage media? It sounds in any way more feasible, as it allows arbitrary access (anytime), doesn't need lots of rocket science and expensive technology, is much easier to maintain, and digital data storage is getting cheaper and cheaper.
