Check your IDM settings. Some file hosts hate it when free user uses more than 1 link or sends more than 1 requests to their servers. In short, most file hosts hate it when a free user tries to use multiple parallel links to download a file from their server. The reason why you couldn't complete the download using IDM and the fact that it took 4 hours to download using Firefox might be the number of connections your IDM and Firefox made to the file host server. Your Firefox took 4 hours to finish the download because it only used 1 (single) connection to the server (hence the slow download speed) but it was safe and "tolerable" by the server since it only allows 1 connection per session for free users while your IDM might use, say, 4 parallel connections to download at the same time resulting the server keep rejecting your requests and eventually stop/disconnect the download. Parallel download is fine with servers like driver vendors (Intel, AMD) but not compatible with many file hosts, especially if you're a free user (or any non-premium one). Try to reduce the max number of connections in your IDM settings to 1 instead of 4 or 8. Or like Savajex suggested go with JDownloader 2 or Mipony. Sorry for my English skill, I'm a Korean.
well i'm not good in computers..but i will setting the idm..maybe it works..thanks..by the way your english is good beter than me..im indonesian though