The task here is to narrow down the issue. Lots of good ideas in post #2.
Hook up via ethernet for an evening and play the same movies/shows. Does the problem occur? If not, then there's nothing for the landlord to do, the issue is either wifi or

TV. Note this is not saying you have to stick with an ethernet connection- this is just putting your wifi bandwidth to the test by eliminating that variable.
If the problem also happens a few times with the ethernet connection too, then there may be something for the landlord to potentially address. Use a computer and Speedtest to repeatedly test & verify that you have a stable connection. Perhaps 150MB is marketing hype at theoretical peak speed and reality is something else. However, even relatively slow broadband will be fast enough for stable video streaming. So 150MB or 25MB is basically the same for these particular purposes.
Your symptoms sound like the bandwidth is unstable (bouncing on & off). But there's all kinds of possibilities: router,

TV, varying demands on your wifi signal (by others in your house or neighbors who have the password, etc), etc. Wifi bandwidth is capped, so 5 people all making demands of it at times can yield your experience. One friendly share of your wifi password with a neighbor can be paid forward with everyone living in the adjoining home(s), dynamically sucking up wifi bandwidth without you even thinking about them doing that (and they may not even realize they are using your wifi either). Easy solution here: change your wifi password. That cuts off everyone who might be eating up a slice of your wifi bandwidth.
If it's community wifi (provided by the landlord), I'd start thinking that last scenario is very likely. A hotel might have fiber optic or GB broadband coming in, but when shared with lots of occupants, the wifi speed can slow down to pitiful speeds. The hotel can claim (even think) they have very robust broadband because they think about the speed sold to them. But they then are slicing it up and sharing it with dozens or hundreds of guests.
So it's still a matter of applying process of elimination.
If you happen to have another

TV, put it in the same place using the same cables and same wifi, and play the same movies/shows at the same time. Does it also show these problems?
The task here is always trying to isolate a single variable and then test it. If you can rule it out, move on to the next until you figure out the issue.