Music from Multiple Computers Trick

This thread on Apple discussions revealed a trick for adding music to your phone from multiple computers:

https://discussions.apple.com/thread/5007069?start=15&tstart=0

1. simply connect your iphone to any other comuter and open itunes
2. open explorer or finder and find the music u want to copy onto iphone/idevice
3. select the music u want then press ctrl-c
4. go back to itunes and select your idevice
5. click on music( in your idevice)
6. press ctrl-v

Although when I follow the steps above, the songs pop in to my iPhone through the iPhone window but remain grey with hollowed out circles, as if they're waiting to fully transfer.

Any idea what's going on?

Also, what would I lose if I decided to sync my music from a new computer? Doesn't erase all media, like whatever photos I've synced, as well as tv/movie/vids/music vids/podcasts?

Thank you!
J

 

if no one has a fix, does anyone know of another way to get music onto my phone? just want to be able to add a playlist, doesn't even need to be on music app..

tried dropbox but it doesn't autoplay through a list of songs, have to play each song individually...