Watch the Oh Daddy, That’s Good! 3 online guitar lesson by Tim Sparks from Post-Modern Fingerstyle Blues
The modes most heavily used in "Oh Daddy" are Hungarian Minor and the Ahava Rabba mode, described and played here. You'll want to get the thumb of your fretting hand into the fingering to manage the descending bass line on the sixth string while voicing the melody that rides above it. The Brazilian Biaio rhythm, heard above in "A Few Bowls Terkish," is used again to great effect in this arrangement.