Well moving only music and videos to the card is not the same as also moving an app. An app on the card will normally require the card be converted to be "Internal" rather than "External" storage. However, that change can mess with downloading direct to the card, since it no longer registers as a normal SD card ("External" storage).
If you leave the app on the phone itself, and leave the SD card as "External" storage, you can do this much easier.
If you want to just move files (photos, videos, music, etc.), not apps, to the SD card you can use the file manager app that is on the device, or if there isn't one you can download and install one to access and move the files. Sadly, they usually only let you move one or two at a time.
To...