It's hard to diagnose these errors and issues you've encountered with the application, but the most common fixes are related to app reinstall, data clearing, security solutions installed, network errors, etc. Here are the common fixes for each one of them:
App Reinstall: Make sure you have created an account within the application and then download it again from the Play Store.
Data Clearing: Go to Settings > Application > All tab > Snapchat. Tap on Clear Data and Clear Cache. Reboot the PC and try again. You might have to add your account again after this procedure.
Security Solutions installed: Remove any Security Suite you have in your phone and restart the phone then try to use the video feature again.
Network Errors: Switch from WiFi to Data and backwards, and if it's possible chooseanother Wifi Network then try again the video feature.
