Maxthon comes with a version of Adobe Flash to ensure the browser is able to play all Flash content upon installation, although this version isn't always the most recent. This is to ensure that any issues related to new releases of Flash don't cause issues with Maxthon. You can force Maxthon to use the most current version of Flash by following the instructions below.
The most recent version of Adobe Flash is available from here: http://get.adobe.com/flash
The "Allow all sites to run plug-ins" option must be enabled in Settings > Advanced.
The MX Flash Updater is recommended to check and update your system and Maxthon Flash version.
An auto-updater tool has also been created by Truuuc which automates the flash install procedures below along with some extra options for languages and other plugins..
If you have any issues with the above, please follow the descriptions linked below.
For Maxthon 4.9.x and later follow the instructions in this post.
For Maxthon 4.4.x and earlier follow the instructions in this post.