One of the best ways to get feedback is to pose questions in the description. Stating something like 'do you feel this would be better darker', or 'should I have defocused the background' shows the viewer that you are looking for comments, and that you are also critical of your own work and therefore likely to be more open to suggestions. Just saying 'comments welcome', although encouraging, does not give a commentator enough to go on, apart from which it is often used as a throwaway comment, such as have a nice day.
On the other hand - if they weren't going to point it out before (because nobody takes you at your word when you say "critique welcome"), then you've lost nothing.
It seemed to work for Cathedral. Quite a nice set of comments on that one. OK so an experiment of one is not statistically valid, but I shall definitely try it again.
But, there is in the body of the online article found at pixiq.com.
I am blame'les's.
In this instance, really ... I am not to be blamed..
I was totally caught unawares! I swear!
... ...
Now if yous will excuse me.. have a bridge to sell..