DESKTOP: Open your wedding video or album in the Chrome browser. Make sure you are on the same Wi-Fi connection as the Chromecast/TV and the 'Cast' button will appear in the bottom-right corner of the video player.
Tap the 'Chromecast' button and the selected video will start playing on the TV.
Android Phone: Open the album in the Chrome browser app. The rest of the steps are the same as Desktop.
iPhone or iPad: Open the album in Safari browser app and then play a video. If you have an Apple TV, you will see the Airplay button on the video controls. Tap on the Airplay icon and select your Apple TV's name. The video will start playing on your TV.
If you don't have a Chromecast or Apple TV, they you can connect your laptop to your TV using an HDMI cable and mirror your laptop's display on your TV.