Magnetdl dot com Browser Redirects
Magnetdl dot com is the domain used by a website that hosts a torrent search engine. As you can imagine, the majority of the content accessed through this search engine, whether through torrent files or magnet links, is illegal and violates copyright laws.
Magnetdl dot com's search engine will return results for just about any game, movie, or music album you can think of, and all of this, as you can also imagine, is distributed illegally, for free.
The website also uses rogue advertising networks and advertisements served through it may lead to unsafe websites that may serve up malware or further links to bad pages. A lot of those pages will also attempt to install potentially unwanted programs on the visitor's system. Those potentially unwanted programs are usually browser hijackers that may cause those redirects.
Even though the most common way of distribution for potentially unwanted programs is bundle installers and software bundles hosted on some free download sites, hijackers and similar PUPs often end up on people's systems through rogue advertisements.
Even if you completely leave aside the aspect with the legality of the content that Magnetdl dot com allows you to search for, the site can still create a nuisance, or worse, through the advertising it serves.
Browser hijackers that cause redirects or funnel user search queries through regular search engines often collect those search queries and resell the collected information to advertisers. None of this happens with the user's explicit consent and is generally pulled off behind their back, so to speak.
This is why similar behaviors are considered unwanted and undesirable. Thankfully, the majority of browser hijackers are relatively easy to remove, either manually, from your browser's addons page, or using your favorite anti-malware suite of choice.