Frozen shoulder is one of those terms that people accept with resignation and it seems like a plausible explanation...until you start to poke around in your own nervous system.
If you've ever been told you have a frozen shoulder, I urge you to look a little bit beyond the (overly) simple mechanical explanation.
What to do about a Frozen Shoulder
If you tried the experiments in the video and saw some changes in your shoulder movement, your best bet is to find someone who can assess your movement on a global (whole-body) level. This person, like a certified Z Health instructor, for example, will be able to see what body parts are not moving when they should be and which ones are when they shouldn't be.
You can alleviate a lot of "frozen" anything in the body with this approach.
If you can't find an instructor near you, the next best thing is to begin a head-to-toe, full-body mobility program, focusing on everything else except your frozen shoulder (the Z Health R-Phase series is the best way to go about this). The number one rule you need to follow is "never move into pain." Instead, you will re-educate your body and all its moving pieces, taking the burden off the parts that are already working too hard.
Fairly quickly (like, within a few good training sessions), you will see a change in how you move, 90% of the time. If you keep it up, you'll prevent further aggravation along these lines.
I have a few more ideas if you're looking for other ways to GET MOVING too.