There is a lot to this ... more than I can to try to explain fully ... especially since it would probably go right over your head (no offense).
What you are trying to do simply won't work. You'll be able to lock the video with the audio for a short period of time (seconds), but that's it.
The issue in a nutshell is that the video is being recorded at one rate while the audio is being recorded at another. A/V Professionals deal with this in a number of ways, but it basically comes down to time code (eg. SMPTE), sample rate, frame rate, etc. If you want to learn more about this topic I would suggest doing some searches on Google; search for "audio video sync
The solution for you: record the audio and video at the same time. If you are playing to pre-recorded music you need to include your audio along with the pre-recorded audio when recording. This means you should not record only your drums, but record your drums AND the play-along music you are listening/playing to. Record this while recording your audio.
Most consumer video cameras will not allow you to send LINE level audio to the camera while recording video. There are ways around this, such as purchasing the appropriate adapter. Consult your owners manual for your video camera to learn about what you need to accomplish this. I does work ... I create video correspondence lessons as well as video for the Drummer Cafe this way.