When using DynDNS (by dyn.com) instead of the Manufacturer's DDNS on Foscam IP Cameras, make sure you enter the DDNS Username and NOT your e-mail address (e-mail is used as Username at dyn.com for authenticating into their website).
find your Dyn username at https://account.dyn.com/profile/
Enable DDNS = checked
DDNS Server = DynDns
Domain = stream-name.dyn-custom-url.com e.g. yatko.dyndns.org
DDNS Username = username (NOT EMAIL!) see: https://account.dyn.com/profile/
DDNS PAssword = your dyn.com password (same as used at dyn.com login)
Note: you'll need DynDNS Pro aka Remote Access (DynDNS) for being able to use their dynamic DNS service: http://dyn.com/remote-access/