Will refusing to do the video be a breach of contract? The contract is terms specified within, unless it's stated that you've to do anything your employer asks, I think the video would be something like extra work which you get paid for and is voluntary, if that's the case, then you don't have to do any video. You can talk to your local public security bureau (PSB) about your options; they normally resolve problems between teachers and their schools. Sometimes this maybe time consuming, if you don't have the time or the cash to wait, then just do the video and start backpacking before it's too late.

Best wishes

Solomon in China