Bouncing Chain After 14/49 Sprocket Conversion

I've recently changed my sprocket configuration to 14/49 and a JT chain 112 link 520 X1R.
Went on a long ride this weekend to a bike festival and noticed the chain bouncing like crazy on load at certain speeds.  If I ease off it's ok but even if I don't load the engine (stay in higher gear) it does this.  Never seen a chain do this.
At the festival I was told the chain seems to have a lot of side play.  It's pretty much brand new.
Here's a video of it.
https://youtu.be/j0BznxVzfhI