আমি কি ব্রাউজার এক্সটেনশন ছাড়া ডাউনলোড করতে পারি?

Yes. Copy a link to a file and GDM offers to download it at once (Options → General → Offer to download links copied to the clipboard, on by default). You can also paste links into Add URL, drag them onto the drop target, add a whole batch, or use the command line. See Adding downloads.