duffster1 i was listening to the teaching, i heard also what you are talking about, but he didnt mention what the blockage was/is.
but i would think that there are many many blockages and its matter of realization and merit and wisdom that you transform into such advanced being that you manifest rainbow body in this life.
i have a book by ChNN named something rainbow body, i havent read it but i think its a story of a yogi and something with rainbow body, might have something else also in it other than the story. if you want it i can send it to you via email or skype.
If the thought of demons
Never rises in your mind,
You need not fear the demon hosts around you.
It is most important to tame your mind within....
In so far as the Ultimate, or the true nature of being is concerned,
there are neither buddhas or demons.
He who frees himself from fear and hope, evil and virtue,
will realize the insubstantial and groundless nature of confusion.
Samsara will then appear as the mahamudra itself….