Normally Skype for Business for Windows Phone won't show meeting content or participant video feeds during a meeting unless you have a Wi-Fi connection. If you turn these options off and aren't connected to Wi-Fi, Skype for Business tries to use your data connection to show screen sharing and video. To change your Wi-Fi settings:
Go to More > Settings > Require Wi-Fi for Video or Require Wi-Fi for Content.
Important: Turning off one or both of these options may result in higher data charges, difficulty viewing shared content or video, or both.