Essentially as long as it's realistic, and things that are depicted are really happening, it should be a good video. Preferable features are:
Woman receiving and giving
Large rectal nozzle or inflatable enema catheter with clear video of preparation and insertion, with realistic patient/sub sounds being made on insertion and inflation.
Higginson bulb in line and in use with frequent squeezing and patient/sub reactions.
Clear video of full bag, preferably clear to monitor volumes and flows.
Video of working flowmeter near rectum.
Video editing so as to convince viewer you are really seeing the actual bag and hose being used and it's not faked.
Appropriate realistic patient/sub moaning and possibly complaining audio.
Preferably obvious evidence of belly expansion.
Massage and position changes with patient/sub commentary on difficulty.
All production/editing values towards proving real not just realistic enema administration.
Expulsion optional but recommended.
Real orgasm during filling or retention preferable.
I personally enjoy some mild BDSM like restraints and gags but not essential.
Secondary kink: add patient/sub wearing rubber and sneakers during enema.
More if I think of it.
MAKE CERTAIN IT IS A REAL ENEMA, PHOTOGRAPHED TO SHOW REALITY, OR DON'T MAKE THE VIDEO.
Eric