I've been having some issues with conditionals lately. Does this work? {if "{mymatrix:total_rows}" > 0}

Turns out this can be rectified by using b.setAttribute("class", "video-container"); Does anyone know why this works and the className doesn't?

I was thinking about this last night and came to a similar solution. I didn't think about Freeform though so good call on that. I have also found a plugin that will help called Channel Images / Files. It works perfectly for what I need but thank you for your answer.

This looks spot on. Thank you very much for your help.