Jittery playback, skipping, etc. - Why is this happening after rendering the video?

Hello!

I made this video for a local shop. I tried rendering the video in multiple resolutions (i.e. 1080, 720, etc.) and on multiple platforms (i.e. Desktop, Youtube and Facebook directly) and it's still the same issue. What's going on here?

Video Link: YouTube

I am using a MacBook Pro with these stats:

MacBook Pro (Retina, 15-inch, Mid 2015)

Processor: 2.2 GHz Intel Core i7

Memory: 16 GB 1600 MHz DDR3

Graphics: Intel Iris Pro 1536 MB

Please help. I'm having a seizure here.

Message was edited by: Musanna Al-Muntasir