Need some help figuring out parts of this song

[coldshot76]

Hey guys

Managed to chance upon this band called "metal elvis' who does rock covers of Elvis.

They did one version of my fav song 'burning love' but mixed it up with some paranoid from Black Sabbath.

The song is in key of D, but theres one part which i cant get.

Its the part just after the first line of the song (16s - 20s) of the video.

The guitarist seems to be playing on a Flat key.

Heres the link http://youtube.com/watch?v=9dAO3J5QJ9w

btw, what kind of distortion is the guy using. sounds cool

 

[Paulo]

going by ear, that riff in 16s-21s, is a rock n roll blues based riff done in chugga tone. if the key is in D, the riff should be D-D - F-F# (repeat 4x)