Using Pipelight worked beautifully for me. It only runs in Firefox, though.
Installing Pipelight
Open up the old terminal (Ctrl+Alt+T) and copy and paste the following commands. To paste into the terminal do Ctrl+Shift+V.
sudo add-apt-repository ppa:pipelight/stable
After adding the PPA, update the sources with
sudo apt-get update
Next, you have to install Pipelight.
sudo apt-get install --install-recommends pipelight-multi
Then, run the below command to update the plugin.
sudo pipelight-plugin --update
Configuring Pipelight
You may have to remove adobe-flashplugin, but I personally did not need to due to it not being installed.
sudo apt-get remove adobe-flashplugin
Then enable all of the necessary plugins
sudo pipelight-plugin --enable flash
Go one-by-one to ensure you're accepting each's license agreement
sudo pipelight-plugin --enable widevine
Finally:
sudo pipelight-plugin --enable silverlight
Then update Pipelight to recognize these plugins.
sudo pipelight-plugin --update
Finally, you must add the plugins to Firefox.
sudo pipelight-plugin --create-mozilla-plugins
Testing it out!
If done correctly, Pipelight should have installed an update version of Flash, Silverlight, and Widevine, which it runs through Wine, as can be seen in the Plugins section of the Add-ons Manager.

Finally, open up Firefox and test 'er out.

Source: https://www.maketecheasier.com/watch-hbo-now-ubuntu/