The Royal Household has invited everyone to watch the wedding of Prince William and Catherine Middleton live on April 29th from 10 a.m. London Time. London Time is five hours ahead of U.S. Eastern standard time, so it will be an early live broadcast for American and Canadian viewers.
The Royal Wedding will be streamed live on The Royal Channel on YouTube, which can be found here.
Here is the invitation from the Royal Household. Take a look: