Short videos on one strategy each:

Take away in chunks using place values of the subtrahend

Add up in chunks using multiplies of ten as bridge numbers

Shifting the number line

Negative number subtraction

Video clip of a teacher using alternate algorithms in the classroom:

At the site http://learner.org/resources/series32.html Watch #15: Bean Sprouts

A slightly different way of looking at renaming place values:

Another way of looking at the standard algorithm.