This extension connects your browser to the popular Internet Download Manager (IDM) tool to enhance your downloading experience by
Dynamic Segmentation
Automatic Antivirus checking
Web site spider and grabber for HTML content
Download Categories.

This extension provides two levels of integration. The first one is the right-click context menu items that the extension appends to the "link", "image", "video" contexts. The second method is the interception of the built-in download manager. When a new download request is sent to the built-in download manager, the extension pauses the job and transfer it to the IDMan. If this transfer is successful, the extension erases the job from the built-in manager.

Other Features:
Increase download speeds by up to 5 times
Supports pause, resume, and scheduling downloads
Audio and video content processing
Zip preview
Comprehensive error recovery and resume capability
Restart broken or interrupted downloads due to lost connections, network problems, computer shutdowns, or unexpected power outages

This download manager supports both FTP and HTTP protocols, you can still get files from FTP servers, although the browser support for FTP is deprecated.
Internet Download Manager has a command-line interface, this extension sends downloading jobs to this tool by calling a configurable command-line option. Note that for this extension to send and receive commands from this download manager, you will need to install a native client. The request to install this client will be displayed on the first usage.

The extension has a built-in tool to extract links from the current page too. You can right-click on the page context and select "Extract Links". A new panel opens and displays all possible downloading links. You can either copy links to the clipboard, or directly send them to IDMan.

--
Legal: This extension has nothing to do with the actual Internet Download Manager tool. It is an open-source integration module to ease the downloading process for those who do not want to manually send links to this application.