Speaking from a software developer standpoint, it wouldn't not (sorry for the double neg) be a big issue. It wouldn't be impossible, but still a pain.
They probably do keep backups just in case, but it'd more than likely be a backup server nobody bothers with. The size of it is pretty easy(ish) to manage, assuming it's ~2.5MB/minute * 60 * 24 = 3.6GB per camera, x average of 8 cameras per apartment (I'm guessing) = ~29GB per 24 hours for an apartment, x 13 = ~ 374GB per 24 hours. It's not an impossible size, but it wouldn't be as simple as just keeping a backup video anymore. They're not going to straight up send you a constant stream of 3.6GB, so they'd need something set up to handle requests for a specific time (e.g. segment the video), which would probably cause a lot more requests to the server than they currently get. Having said that, they'd probably need to setup an additional server to act as content delivery. Because of the nature of the site, most existing solutions would probably reject it. Not worth the hassle for their current user base.
EDIT: Also having highlights would be more difficult. It's either automated, which wouldn't be very accurate for what users want, or manual, which would be a headache.
The easiest way to improve RLC is to get better apartments.