Where do AVI files transferred by Airdrop to an iPhone go?

I've just copied a couple of videos from my Macbook pro to iPhone 6 plus . The MP4 file goes into the Photos app, but the AVI files seemingly completed the transfer but then can't be found. Are they still on the phone? If so, where are they and how would I access them? I've looked in the Videos app and I've also got an app called PlayerXtreme that is supposed to play the file type, but it's not in either app?? plz help