You can now install Google Cast in Opera browser. Like Google Chrome and Firefox, Opera also itself maintains an add-ons site for users to install apps, themes and extensions in the browser, but its not possible to install Chrome extensions in Chromium-based Opera browser. For instance, you don’t find the Google Cast extension on Opera add-ons gallery because it is a Chrome extension, but if you want to install it in Opera –FYI, latest Opera developer has added support for ChromeCast –you can, here is how.
Installing Google Cast extension from Chrome Web Store in Opera
1. First install Download Chrome Extension (link), this extension upon installing allows getting extensions from the Web Store in Opera browser.
2. Next, visit Chrome Web Store in Opera, find and install Google Cast extension by clicking on ‘Add to Opera‘ button (without activating this extension, Web Store shows Available on Chrome button).
Note: Opera doesn’t support Apps, and this extension doesn’t support Chrome theme format, so you can only install Chrome extensions.