Question

understanding the concepts regarding miller indices

Answer 1

Do you mean why they're useful or how to use them?
If it's the former then I think it's mainly a way of highlighting a particular plane of the unit cell, which becomes important when identifying which plane different unit cell structures 'slip' along and why x-rays are cancelled out at certain angles etc. (Sessions 15-20 go through this.)

If it's how to use them, to me it felt like Sadoway and the archived lecture notes went over them quite quickly, but I found this site useful:
http://www.chem.qmul.ac.uk/surfaces/scc/scat1_1b.htm
The graphic in on this site also made a lot more sense to me:
http://chemistry.bd.psu.edu/jircitano/Miller.html

As long as you remember to take the reciprocal of the numbers going out from the origin, then connect the dots and make sure you take zero to be infinity it's not too bad.

Answer 2

This video (and channel) is also very clear in explaining it
http://youtu.be/pMTA_wiY784