Is gst is mandatory for small seller with personal ecom site

I saw a video :-

https://www.youtube.com/watch?v=evD_bWN1P_4

As per my information every person who sells through Online platform has to register in GST even if his sales is Rs 1/-.

@ Video :- Is there a difference in a ecommerce facilitator (flipkart, ebay, snapdeal) and small seller (owner of small personal ecommerce site) ? as this video says that small seller need not to register in gst since it will be not a facilitator.

Will that small ecommerce seller selling in same state would considered as ecommerce and will he need to register in gst ?

Pl calrify.