First of all, trying to detect an alien radio signal, unless they have a transmitter in the terawatt range, is fruitless when you consider the radio noise that would be emitted by the nearby sun and any gas giants in the system. Trying to pick out a coherent radio signal against this noise is akin to trying to spot a candle in front of a searchlight. It is true that our deep-space probes can communicate with us in only a few watts, but that's because they're on a very tight beam - which is thus not susceptible to interception by anyone outside of the line of transmission.
Broadcast radio, on the other hand, is subject to the inverse square law, as is any form of EM emission. At interstellar distances, the signal strength per square metre of reception area is negligible, and most likely drowned out by other radio sources anyway. I would go so far to consider that this, and not the actual absence of alien civilisations, is the main reason SETI hasn't discovered anything, and probably never will.
Even if we could, the chances of being able to decode the signal are near zero. For one thing, we're assuming the aliens' visual bandwidth is the same as ours - they might "see" in the infrared, or ultraviolet. Or they might communicate by smell rather than visually, and the signal may be describing various molecular combinations rather than graphical information. Even if they do see in the same EM band as we do, there are very many combinations of possible viewing resolutions and display patterns (e.g. they might have round screens with the scan beam spiraling in or out instead of left-right, top-bottom (or any other rectangular order). Further, they could use any combination of colours besides RGB to build their images. This would make decoding the signal all but impossible.
As to DRM in the signals, well, I should hope that any enlightened civilisation would not operate under the same principles of greed, selfishness and megalomania as humans do. If the way humanity behaves is an indication of the behaviour of intelligent life in general, then the Universe is in a bad way. Given human nature, the prospect of meeting a race that thinks like us that might have superior firepower is one that would destroy humanity as surely as we would destroy a civilisation of Bronze-age or even Victorian-age creatures on contact. For profit, of course.