The linked video clearly makes the opposite point, that holding kids back does not affect club sports with fixed age limits. It does affect high school and college, which is why holding back is so common in football where recruitment is more focused on high school compared to soccer.So they net is that holding back kids is common in basketball and rules are implemented to accommodate it.
For those that think soccer parents won't hold their kids back for wins if given the opportunity you're sadly mistaken.
Here's a proponent of holding players back 1 and 2 years.