All personal information yourself or your cast members provide is encrypted and access is controlled. Information you upload will not be released to any 3rd party without a UK or US court order for the protection of minors, human trafficking, where vulnerable people maybe at risk or as part of a criminal investigation.
As a cast member, nothing!
Once you create an event you will be provided with a QR code which you can display on a phone, tablet or laptop, or print off for use on the day of the event. Cast members can scan this QR code to check in to your event, creating an electronic record of their attendence with their consent and identity details securely attached.
Each event has a "reference code". You'll need to add this to the clip on the service you're using to upload an distribute it.
Exactly how this works will vary by service, however since the code alone means nothing, you could even put it in the publically available description or title.