IDM is great, but it isn't free, my patched build kept nagging with popups, and recently stopped working — so I looked for a replacement.
Neat Download Manager (NDM) is a dynamic segmented downloader for Windows and macOS. It's a solid IDM alternative: it efficiently grabs videos, audio and files from web pages. Usage is identical to IDM — install the browser extension and NDM auto-detects downloads. Free and handy, worth having.