Many movies have depicted live mummifications (famously in the Mummy series) for grave crimes against the pharaohs. Was this really a practice in ancient Egypt as punishment?
Its very doubtful; equally it is notoriously hard to prove a negative, and so not being able to bring to mind any recorded instances of mummification being performed on people whilst still alive I would say no, it was not done.
It is worth remembering that mummification was a precises and sacred ritual, taking some 70 days to complete, done with the intention of preserving and preparing the body so that it may be of use in sustaining the spirit in the afterlife. It seems even more doubtful then that a peron admitted of a grave offence would be allowed such ceremony.
I would say though that it is probable that every single method of inflicting pain and death on a human being that can be imagined has been practised at one time, which of course would include mummification of the living. However I would still think, that in the context of your question, the answer is no.
In addition to the excellent arguments of @user995689, I think it would be difficult to imagine that granting eternal life to someone would be perceived as a punishment. Mummification gives the soul access to eternity; that is not punishment.
Is there any record of this "punishment" prior to hollywood? Any record of this punishment from any source that has a legitimate background in Egyptology?
This isn't in Egypt, but religious self-mummification through starvation is a known practice in several Asian traditions. The idea is to leave a corpse that will not rot, which must contain as little water and fat as possible. Simply starving to death will not cause this outcome. The practice is called Sokushinbutsu among Buddhists and Sallekhana among Jains.