That's congruent to what Abbott Tryphon wrote (in the blog post you started with):
"Although early Christians inherited a sabbath practice from the Mosaic Law of remembering the sabbath day on Saturday, the position of both the Eastern and Western Churches came to observe the Lord’s Day as Sunday. Thus supplanting the Sabbath commandment of the Jews, they chose to celebrate the Christian community’s deliverance from captivity to sin, Satan, and worldly passions, made possible by the resurrection on the first day of the week. Early Christians observed the seventh day Sabbath with prayer and rest, but they also gathered on the first day. By the 4th century, the Church was officially observing the first day, Sunday, as their day of rest, not the seventh."
So, my apologies. I was wrong. I guess Sunday is the Sabbath for us. If that's a problem for you, I invite you to re-watch the video you posted and ask yourself if you are not making the Judaic sabbath day your god.