Yes, Watch Party is not a hack. The sole purpose of Watch Party is to help synchronize the playing/pausing on streamed content.
Watch Party is built to not be in your way but, it can be hidden by going clicking on the Watch Party extension (in the top right of Chrome toolbar), and switching the show / hide switch.
You can alternatively go to the Chrome Extensions page (chrome://extensions) and toggling the little blue switch next to Watch Party.
Watch Party is built to be completely free, all the costs are paid by the developer alone. While no payment is needed, any small donation helps make sure I can keep the servers up and running. You can request more details by reaching out to admin@chromewatchparty.com.
CONTACTTo have access to Watch Party in fullscreen use the fullscreen button in the bottom left corner of the sidebar.
If you started the party, you can simply join the party from a different place to change the party location.
You can turn off the chat notifications from the title card in the sidebar. Click on the title card to see the setting.
Click on the GIF button next to the message input box, start searching! Scroll to the right to load more results.
Click on the title card in the sidebar, and click on the End Party button. Ending a party immediately deletes all data.