Hello Mel Anderson - I happen to like Rebecca Snowball a lot too! Although I haven't watched every single video of hers, I've loved whatever I have tried thus far. My favorite of hers is - "Soulful Sweat." It is a pretty "challenging" video!!! And if that is particularly what you like about her, then may I suggest:

(a) Laura Burkharts - "45-minute Vinyasa Flow"
Link: Well-Balanced Flow: 45-minute Vinyasa Flow Class
Or perhaps
(b) Beth Stuarts - "Nonstop Flow" - Link: Flow Till You Glow: Nonstop Flow

I have noticed that "some" of Rebecca Snowballs Videos are also slow paced, as she takes the time to explain the poses. That doesn't mean that they are any easier, as holding a pose for long is a different kind of challenge in itself. But if that if what you liked about her, then here are a few other suggestions:

(c) Dana Damaras - "Grounding Chakra Flow"
Link: Grounding Chakra Flow
(d) Rocky Herons - "Full Body Stretch"
Link: Lean & Strong Yoga: Full Body Strength
(e) Tammy Jones Mittells - "Vinyasa For Core"
Link: Vinyasa for the Core
(f) Morgan Barry Levays - "Neck & Shoulder Flow"
Link: Neck and Shoulders Flow

They are all great instructors in their own way, and I hope you will find some of these videos to keep you engaged until Grokker adds more to their collection! :-)

I think grokker should post new videos with Rebecca snowball. her yoga videos are sensational! Can anyone help with this?