The two most recent episodes of the Horn Notes Video Podcast both relate to tuning.
The newest episode is one featuring Gustavo Camacho with a focus on tuning with drones. Dr. Camacho is horn professor at Western Washington University, having previously taught for four years at the Interlochen Arts Academy. He earned his MM and DMA (2011) from Arizona State, and has clearly given some thought to practical solutions toward improving intonation. In particular, during his time at Interlochen, he developed a four step plan to improve intonation with drones. For more on this listen below.
The other episode is related, with a focus on a product that will help your tuning, The Brass Gym for Horn. I led a group warm-up based on The Brass Gym at the recent Southwest Horn Conference, in part because there are good materials there, but also because the horn version was released in 2007, ten years ago this year! Background on the publication (I was the editor), and a number of tips are presented in this short video. And, as always, be watching for more episodes.