I went to the official website that lists what you can and can't take over the border, but I am having trouble figuring out one thing. 
It says you have to have receipts of all items bought there when returning to the US.
What if you take something with you there, how do you prove it was yours and not bought while there?
The items are movies, it's 9 hour drive there and I planned to take along the laptop and a bunch of movies to help pass the time. Now though I am wondering if I should skip it because I saw CD's and DVD's listed as items you need to show receipts for, and I don't have them anymore.
So, boiled down... dumb question is "can I take those kind of things back and forth over the border with no problem or should I just skip it?".

It says you have to have receipts of all items bought there when returning to the US.
What if you take something with you there, how do you prove it was yours and not bought while there?
The items are movies, it's 9 hour drive there and I planned to take along the laptop and a bunch of movies to help pass the time. Now though I am wondering if I should skip it because I saw CD's and DVD's listed as items you need to show receipts for, and I don't have them anymore.
So, boiled down... dumb question is "can I take those kind of things back and forth over the border with no problem or should I just skip it?".

It was a lot to take in!