Hmmm its quite funny that our nexus 5 is a bluetooth speaker for other phones xd. But ive have send a file. Just turn off on other phone music streamming to your nexus, an then use program, bluetooth file transfer. In this way i could send files to other phone. Not tested it in back way, i mean send file to nexus 5. U can do this and inform us :D. It should work, you can read this feature in app.