----- I am not an ESL teacher -----
Well, he could have used the present 'want' form here, no problem.
Did you hear clearly he say 'wanted'?
The past tense here is used to express a kind of indirectness, some uncertainty, something like: "If you let me, I will share with you ... "
Have you ever wondered why we say for example:
"I would like to say something ... " instead of the more direct
"I want to say something ... " ?
I guess in you example, "I just wanted to share ... " stands for
"I would like to share ..."
Remarkably, a google search of "just wanted to say" produced more hits than "just want to say." On the other hand, without the word 'just', a google search of "wanted to say" returned less hits than "want to say."
Student or Learner