Your VIDEO files should work in both places, as long as they are "standard" video so both programs have the correct codecs installed
I very seriously doubt that your PROJECT files are interchangeable
If the versions are close to coincidental, such as PrPro CS 5.5, and PrE 10, you should have pretty good luck, going from PrE to PrPro, but you cannot go the other way - PrPro to PrE.
Now, much of the success, with going from PrE to PrPro will be the complexity of the Project. There are things that will NOT translate from PrE to PrPro, such as some of the 3rd party Effects and Transitions, that PrE has, but which are missing in PrPRo. Also, functions, like Themes and Instant Movies, do not exist in PrPro. The more simple the Project, the greater the likelihood, that the PrE PREL (Project file), will Open, or Import into PrPro - you just cannot go the other direction.