That’s not bad at all!
Amanda, Amanda, Amanda and I have done this quite a bit, and learned some lessons along the way, so perhaps we can help.
You’re always going to need some feedback while you’re recording to keep in time with the other versions of yourself, and ideally, you’ll be able to hear your other selves actually playing so you can be in tune with them too. You can use headphones for this, or earbuds if you want to be more discreet. I now have a pair of in-ear monitors which are ideal for the job.
It’s very common in film and video to record the sound separately from video and then sync them up again at the edit stage. You can, as you say, record sound on your Tascam 4-track and a nice mic, but also record ‘scratch’ sound on your phone along with the video. The Tascam approach will always be way better than any sound you can capture on your phone (unless you invest in an external mic for your phone and use something other than its native video app for capturing sound).
What we tend to do is to record all the music tracks before beginning any video work. We use a click track or a metronome to set a regular tempo, and, on at least one track, count aloud for a bar, then leave a silent bar before playing the first bar of the music.
Then, when shooting the video, we have the music - and the counting - playing in headphones or earbuds. We know when to begin from the count, and we can play along with the music we hear. (We might also occasionally record dialogue prompts along with the music, if there’s dialogue - Amanda’s not very good at learning her lines).
Also, when shooting the video, for each track, we click fingers or clap along with the count-in. These clicks or claps appear as clear, clean spikes on the sound trace for each video track in our editing software, so it’s easy to zoom in close and line them up very accurately. If the clicks line up, the music should be perfectly in time.
One option is to not use the sound from when you shot the video at all, but simply use your pre-recorded sound. If you do this, you don’t have to worry about playing into a microphone while you’re performing on-camera. Effectively, you’re miming for the benefit of the video. (Just miming wouldn’t look real at all, but playing along with the music the viewer is going to hear looks real enough!)
Sony Vegas can, I believe, do all of this, although learning the details of any full-scale editing software can be a bit of a process. It’s worth it!
On the video side, be thoughtful about your framing - there’s a lot of unnecessary headroom in your video. You don’t have to use your phone vertically; you may do better with it set horizontally. You can re-size and crop each video frame in your editor to make the maximum use of the final video frame and have less of the black bars around the edges.
Be aware, too, that some cameras, or camera apps for phones, use variable frame rates, and this can cause your synchronisation between video and separately-recorded sound to drift apart. You can download and install some pretty nice camera apps which allow you to control things like this - also frame rate, shutter speed, ISO and various other things. Controlling these things yourself, rather than just using ‘auto-everything’ can fix some other problems you might otherwise encounter.
It’s a nice touch to mix down your music recording in stereo, and use your ‘pan’ controls to place the sound appropriately to the arrangements to yourselves in the final video. So, for example, in your recording of Have Mercy, the trombonist appearing on the right of the screen appears to be coming mainly from the right-hand speaker/channel/earbud, and the left-hand player from the left-hand speaker.
There are lots more videos Amanda and I made on our channel
here, and we were inspired originally by
Dan and Dan. The
Daily Mail song is a classic, and their
Palindromic Sketch is a tour de force.
(I should make it clear that if you really do have identical siblings, as of course I do, none of this is absolutely necessary. But Amanda always seems to be busy washing her hair, Amanda never seems to be able to learn her lines or hit high notes accurately, and Bass Amanda... well, she’s just mysterious. So it’s possible that from time to time, we might use one or more of these tricks to make it
look as if more of us were present at the video shoot than there really were. It’s not dishonest really...)
I then uploaded the two videos into the software and just tried to line them up visually in the playlist editor. Considering what I had to work with it didn't come out too bad but I'd like better quality audio. There are devices that do this for not too much $$ but I'm going to try something else first.
Thanks for the tip about head room. 