How To Manually Add Music To iPhone iPod iPad Without iTunes Sync
Check more details about Bridge app for iOS here
Adding Music Without iTunes Sync
Step 1 : Launch Bridge and go to the files tab.
Step 2 : From the list of folders, browse to the folder location where you have downloaded the music. If you have used Safari Download Manager to download music files then the default location for the downloaded files would be var/mobile/media/downloads
Step 3 : Tap on the song that you'd like to import to the music library.
Step 4 : Add the details and if you wish to add an album art image then you can add that too.
Step 5 : Once you are done with labeling, simply tap on the import button.
Step 6 : Once import is complete you can go to the music app to confirm the import was successful.
Check out ProTube to download videos from YouTube and import them using Bridge!