Just installed this app
When I try to use the main camera on my Galaxy S3 I only see something like white noise.
Check this images which looks very similar:
When using the front camera, it works fine.
Tried to use the main camera and it works perfect with other apps.
Will try to upload a screen capture or screenrecord.
These links may also be of interest:
I am not really sure here but it might be a focus issue. It sounds strange but if I try to be worse than basic now, if I was to see this happen I'd try to move fingers slowly in front of the lens to check that it is focusing. Move it at different distances and see where/if it focuses. You probably already tried but worth a mention, at least I hope so.