My first Halo 5 montage, want advice on it.

[DivinePaladin]

A few suggestions:
If a clip is taking a long time between moments A and B, and neither are exceptional, I'd leave them out, or do a full cut between them. It feels a bit cheap to spend like five seconds watching you get hit or whatever in double time just to see a double kill from the grave or what have you.
Don't do Grifball - it's easy pickin's and the stuff you showed is tame (no offense intended here) compared to the Grifball stuff people wanna see. Moreover, Grifball is laggy and we see that in your second Grifball clip. There shouldn't be much question to the kills being made.
You're dying too much in these clips. Montages feel a bit less satisfying when you die once a minute, even if the post death is a kill from the grave. This also adds to point 2, because you show your death in Grifball just to have the Killionaire pop up.

That's mostly it though. Otherwise it's solid. Keep in mind I may not be as wowed because I was a top tier Reach player online for the first six months of the game so I've been involved in some CRAZY shit. Just because it may not personally wow me doesn't mean it's not necessarily good! This goes particularly for the death parts I mentioned earlier (I'd wager 10% of my deaths in Reach ended with at least one from the grave kill).

Oh, also, vary your clip lengths. Nobody wants to see stretches of long clip after long clip. If we're watching montages we're looking 100% for short bursts of awesome - and like I said before, if it's long it better be super worth it.