My trainer would be telling you that you ride like a trail rider. Most of the time trail riders are just a passenger vs. being a rider. This mare looks like she needs a little help from her rider (you) in order to be consistent at the canter (she's not what I would consider loping).
A little change in your riding position will start to give her the help she needs. Scoot yourself forward in the saddle so that you are sitting in the middle - between pommel & cantle. This should let your leg drop straight down from your hip. Shoulders - hip - heel all need to be in line. It will also cause your leg to be closer to her belly, which is ok. You want to feel like you are giving her a gentle hug with your legs. The spur training should allow her to accept this light contact without having her rush forward to go faster.
She is falling out of the canter several times throughout the video. She may need a chiropractic adjustment, hock injections, or other medical attention. In the meantime, you will need to push her forward into the bridle to help her maintain her gait. A spur trained horse has a button that you squeeze to make her stop, but she will also have a button that you squeeze (or probably bump) to get her to move up & hold herself together. This part of western pleasure riding is a lot of feel & timing, which takes many hours/months/years of practice to learn & perfect. For right now, just be aware of the feeling of her good lope vs her falling out of the lope. Your reaction time will be slow right now & it won't make her look her best, but you will develop your feel & timing so that you can help her more & more to get her looking her best.
Perfect Jin N Scotch - 2004 APHA Palomino Overo Gelding - Western Pleasure and Showmanship
Hanks Rainy Sky - 1998 Black and White Tobiano Paint Gelding - relaxing rides and blazing trails