Is it possible to split off a neighbor's Comcast cable to provide service to my condo?

The cable company will run ONE or more cable lines to a structure. Numerous things drive this decision, and I do believe there is a code they also must follow. This is just an FYI.

That said:

The only thing that would actually prevent the provider from splitting off to "other rooms on the same structure" is signal loss and signal quality measurements.

So is it possible to run multiple units from "one service line" via a number of splitters/taps? ABSOLUTELY and this is standard practice.

When the signal degrades beyond a serviceable quality and equipment cannot operate properly, or customers are complaining of outages, they may rerun cables (in near total futility) OR a wise technician will reduce the taps, use boosters, run another drop, etc.

So you know, every time you split a signal there is an inherent loss in dB. Drop below an acceptable level, and equipment will not perform optimally.

it's likely that the internal cabling in your residence is RG-59U cable, which is insufficient for today's high-bandwidth services. There are really no code issues with installs such as these, as they fall into the "no-voltage" or "signal" type of wiring. There are code considerations but those have nothing to do with splitting off the line for more than one outlet or more than one client.

As long as the service feed to your shared connection is not the one that would get disconnected for non-payment by the other party, you're in good shape. Design criteria for cable television includes sufficient signal strength for multiple outlets, usually maxed at 4 but sometimes the design allows for only two (a single split) unless additional compensation is performed.

I can see that one leg of the splitter also has attached what appears to be a filter device. This implies that the other party is receiving services that you are not. It's unusual to have this sort of thing readily accessible. It's a simple (and not-legal) matter to remove the filter to access the service. It's also possible that the filter provides only a specific service to your drop. Removing that filter might deny you service.