http://gg.gg/18ieyk
The differences are fairly small and subtle, but here's what I feel.
1. I want you standing up when the judge enters the court. You never stand up
when the judge comes in. This time you'd better remember. To me, there's a
hint of exasperation.
2. I want you to stand up when the judge enters the court. A pretty neutral
way to say it.
3. I want you to be standing up when the judge enters the court. I want you
to stand up before the judge enters.
https://www.englishforward.com/question/want-someone-to-v-ving-1692036876