If you don't have the rights to share that ROM then you likely don't want to share It.
ROM sites are required to not hold a ROM for more than 24hrs or 48hrs, and I believe they rotate their ~~URLs~~ files in order to ~~circumvent~~ abide by that rule.
Frankly, why bother at all? Why not link to a ROM website directly? Unless ONLY YOU have that ROM, then it's more of a risk than a feature.