​The Khronos Group had several session on BOF Day at SIGGRAPH 2019. Most of the slides and video are now online:

• glTF: Efficient 3D Models: Video | Slides
  
• WebGL: Latest Techniques: Video | Slides
  
• Standardizing All the Realities: A Look at OpenXR: Video | Slides
  
• Vulkan Sessions: Video | Slides
  
• 3D Commerce: Video | Slides
  

Be sure to visit the event page for a detailed list of links to all the presentations and videos.