Cannot watch iTunes purchased media with old Apple ID
If you remember the old id and still have access to the email account associated with it, you can definitely reset the password and then authorize your macbook to play these files.

iForgot will prompt you for information, but it should allow a password reset via email, not just questions. If you still cannot remember/access the info, I recommend sending apple an email via their iTunes store support and see if they can identify you via other means.

http://www.apple.com/support/itunes/contact.html