I have connected my MacBook to my TV using HDMI and adapters but all I get is the screensaver. How do I connect so I can watch films online?
Go to System Preferences ---> Displays ---> Arrangement
Check the Mirror Displays Option.
This will make anything visible on primary display available on your secondary display. So you can just Play movie and it will show on both screens
Do you also know how to connect the sound? I did the mirror thing and so now i see the screen but I can't hear through the TV speakers
Your macbook is treating the other display as a second monitor, and since it is not in use, its showing you the screensaver on it. This is my diagnosis of your issue. Tinker around the display settings to share display on more than one monitor, and not use second monitor. sharing will show same data on both displays, while using 2nd monitor (what you are doing right now), will display different matter on both monitors.