Amy Bunger’s “How Did You Do That?” series of DVDs has demonstrated to stitchers many great techniques.
There are 11 videos in all in the series. Besides Amy they also feature Kelly Clark and Tony Minieri.
Robin King, who worked on the series, summarizes them in this blog post: http://needlepointstudyhall.blogspot.com/2014/12/howd-you-do-that-needlepoint-dvds-part-1.html
The videos are available at your local needlepoint shop.