Re: not yours
Having a legitimate disk copy of a given movie would seem to be a pretty good license to freely download a working copy from the Internet, in the event that the rights holder somehow revoked the functionality of the physical disk.
It would certainly be a case of go ahead, and if they argue the point then 'see you in court'.
The less likely that this approach is considered to be acceptable, then the more likely that you live in a country where the supremacy of common law has been replaced with lobbyists. Which would be "sad".