Hi, Dude,
In English, certain verbs or verb phrases are followed by V-ing with a passive meaning. These include need, want, require, be worth.
For you to understand the rationale underlying this idiomatic use, you can imagine that the V-ing corresponds to a tacit subject's action, with the stated subject being the object of that action, for example:
What an amazing explanation! Thanks a lot.
Your examples are very helpful.
'Watching' and 'painting in your examples are gerund, correct?
If then, I have one more thing to ask.
How can I distinguish 'needs somebody painting it' and ' needs somebody to painting it'?
Still need your help, thanks in advance.
This play is worth (your) watching (it)
- This wall needs (somebody) painting (it)