Video ads require a good internet connection to download and play. Your video offers will vary based on what is available in your region from the ad networks we use. If the app hangs on the Loading box, it is looking for an ad. If you don't have any offers available, you can try force closing and reloading the app as this tells it to look for new ads. Otherwise as long as you have a good internet connection there are no other tricks to improving video ad availability.
If you are stuck at a black screen, this it means the app detected an ad but is experiencing an error downloading it. This is likely caused by a poor connection. Please try turning the device off and back on and confirm you have a good internet connection. Something else to try, go into the Bit City Menu and uncheck and recheck the Video Offers button and try again. If it still isn't working, you may need to give it some time and try again later.