According to the tips in the above figure, the steps to install the YouTube convertor extension are as follows:
First, search for tampermonkey in chrome, find it and add it to your browser.
Second, return to the current page to install and download the YouTube function for the extension program.
Finally, check whether the installation is successful. You can watch the content of Youtube. A red download function button will be added under the video or audio, which means the installation is successful. You can download the content directly on YouTube.