Please note that in order to watch streaming cams via an Alexa-enabled video streaming device, you must be a Surfline Premium Member and you must link your Premium Account.
All Echo devices with a screen will stream Surfline cameras for Premium Members who have linked their accounts. Fire TV Cube will stream Surfline Cameras (however, Fire TV will not).
Try Surfline Premium here.
For assistance regarding the process required to link your Surfline Premium Account with Alexa, you can view the article linked here.