Video playback sync issues

I'm having some issues with video playback sync. I have two spheres with 1280px square videos, and you can see the seam because of the slightly out-of-sync videos. I can't use a single video because the quality is too low for 360 scenes, so I need to split them into two videos at the 1280px max size.

Here's the preloader script. I think it's mostly working, but maybe there's some way to gain more control over playback timing.

//@input Asset.Texture video1
//@input Asset.Texture video2

var loadStatus = {
    [LoadStatus.Idle]: 'Idle',
    [LoadStatus.Loading]: 'Loading',
    [LoadStatus.Loaded]: 'Loaded',
}

var videoStatus = {
    [VideoStatus.Paused]: 'Paused',
    [VideoStatus.Playing]: 'Playing',
    [VideoStatus.Preparing]: 'Preparing',
    [VideoStatus.Stopped]: 'Stopped'
}

var readyCount = 0
function checkReady(v){
    readyCount++
    print('ready: ' + v.name)
    print('load status: ' + loadStatus[v.control.getLoadStatus()])
    print('video status: ' + videoStatus[v.control.getStatus()])
    v.control.pause()
    if(readyCount == 2){
        print('1: ' + videoStatus[script.video1.control.getStatus()])
        print('2: ' + videoStatus[script.video2.control.getStatus()])
        script.video1.control.resume()
        script.video2.control.resume()
    }
}

script.video1.control.setOnReady(function(){checkReady(script.video1)})
script.video2.control.setOnReady(function(){checkReady(script.video2)})
script.video1.control.play(-1)
script.video2.control.play(-1)

Aside from that, I found that I needed to put the video textures into screen textures, otherwise only one of the videos would play.

I also found this related thread, but the solution there won't work for me because of the video size limitations. I'm sure this 1280px limitation is a device optimization, but it would be really nice if it was lifted ;)