"Russia was trying to take over the film industry? It sounds a bit far fetche that's all."
Not far fetched at all. Control all forms of media. Control education. Reap the benefits years later with a weakened opponent. That was the plan. Post #6 gives a brief synopsis.
It wasn't a crime to be a communist per se. Some of the communist activities (i.e., espionage) were clearly illegal and some were benign (but were sometimes used to fund the illegal activities).
There are a few books out there about the Venona Transcripts that go into great detail. You could also google Venona and get the NSA's website that has some of them online.
Oops. Make that post #5.