This is consistent with my understanding (from my leagal eagal). There is a right to make a personal and archival copy, including media shifting of any non-copy protected dvd. The DMCA, which the movie makers are now vigorously attempting to enforce to eliminate the fair use doctrine, and apparently using customs to do it, forbids working around the encrypt, or aiding someone in doing it.
To avoid customs problems, there is no need to tell customs how things get into the computer. The OP wasn't dinged for having them, only when he answered how they got there. No answer is an answer to a probing question. Remember, anything you say can and will be used against you, except exculpatory statements.
As for copying copy protected DVD, even that may be ok under DMCA if the copy protection is copied intact. IE you don't decode the encryption or otherwise disable this, from what I am told.
Practically there are a number of mechanisms to easily do this, but under the DMCA if you discuss any of these you are in violation of the DMCA and can be prosecuted, so I can't discuss the technology, but I speculate your average community college programmer could write code quickly to do this.
As for real copyright violations, these work strongly in favor of the creator. We have a former employee who violated our company's copyrights for commercial gain when he reneged on a severance agreement. Our legal expense is minimal, his astronomical, even if he wins (doubtful) and the damages are staggering if he loses.
So, archive/media shift your owned dvds, don't defeat the copy protection system and you're likely to be ok, even if they find a few flicks on the computer, and remember you can say nothing if it might be incriminating.