- Modified version

In most of the videos you can see the student standing still as a dummy, letting the instructor attack him with all kinds of fancy movements. Their CHI SAO is just a rapid rolling movement. There is no CHI in it at all. Impressive to the eyes, but doubtful of practical value.

ONLY FOR THE SHOW.

- Imitation version

Since the Ip Man movie plus one and a half years of the Covid-19 problem. Some person self learnt it with "no instructor". They copied and imitated the Wing Chun basic hand movements from the movie and videos. Then they teach the unsuspecting public with wrong explanation and application. These kinds of people are...

WING CHUN OPPORTUNISTS.

The Authentic Version.

The blind leading the blind:

The more popular Wing Chun becomes the lower its quality becomes.
90% are modified ones.
Some don't even look like Wing Chun.
The best way to look for an authentic one is to compare any person's video to IP man's one. The more the differences, the less authentic.

Concerning Chi Sau:

There are only 3 or 4 of IP man's direct students still alive. They are too old to do proper Chi Sao with their students.
In fact, the art of proper Chi Sau's movements and techniques are reaching to the edge of extinction.
Simply because Chi Sao is easy to copy from anyone, but difficult to learn even from a good Sifu.