Unable to play H.265 videos

I tried asking around and they said it might be my hardware as my MBP is an older generation but no concrete answers yet.

Intel says “Any 7th Gen Intel Core processor or above” for 4K UHD playback, as those chips have special provisions to help with HEVC decoding. A MacBook Pro Core i5 2.9 GHz 13" Early 2015 has an i5-5287U ‘Broadwell’ chip, which is 5th generation for Intel. Meaning that notebook will not be as capable on HEVC decoding as with 7th generation Intel ‘Kaby Lake’ processor chip, such as featured on e.g. Mid 2017 MacBook Pros and newer.

Try playing in IINA player. I found it quite smooth playback for demanding videos.

H.265 can have a wide variety of parameters, some of which may make playback a bit more demanding on modest systems. Does your drone camera have configuration settings?

There could be something wrong, e.g. a background process that hinders other applications. But that would need examination, e.g. using EtreCheck. We’ll have a look at its report, if you want.