1. What Is Streaming and What Is Downloading?
First, let’s make sure we have the same idea about what streaming and downloading are. When you download a file, you copy it from the Internet onto your local device. You physically have the file, the whole of it, at your disposal. You can play it as many times you like. When you stream a file, you don’t physically have it on your computer. The file is somewhere on a server, and you are receiving portions (i.e. streams of data) of it at a time. Streaming is very similar to listening to the radio or watching TV – you don’t have to do anything special (e.g. download the file) to see it/listen to it but after the song/movie is over, you don’t physically have it.
2. If You Plan to Play the File Multiple Times, Then Download It
You can’t say streaming is better than downloading or vice versa. As you see from their explanations, they have different pros and cons. This means it depends on your particular circumstances – in one case streaming is the wiser choice, while in other cases it isn’t. Basically, if you will be playing the file multiple times, it’s better to download it. You download it once and can watch it as many times you want. And you don’t need an Internet connection to play it – this makes a huge difference if you are on a plane or somewhere else where you either have no Internet at all or it’s not fast.
With streaming you have to transfer the data (almost) every time you play it. I say almost because if you stream a file and it gets into your browser’s cache, AND you don’t close the browser between the replays, AND it doesn’t get overwritten from the cache, you might be able to play it without downloading it again. However, technically in this case you are not streaming directly – you are replaying a download. It makes no difference that this isn’t a file you explicitly downloaded – it’s still a download because it resides locally on your hard drive. (Your browser’s cache IS on your hard drive and not on some server, right?) Also, if a file is a really precious one, you’d better download it and keep it safe. In this case you can’t rely on streaming – the file might be gone at any time.
3. If You Are Okay with Lower Quality, Then Stream It
If the file you plan to watch/listen to isn’t a very important one, and it makes no sense to download it locally and keep it, streaming is the better choice. What is more, if it turns out you don’t like what’s in the file, you can stop it any time. In this case you don’t have to download the whole file just to see it’s not what you like, and you play only the first seconds or minutes of it and move on. This is a huge bandwidth saver – you don’t download stuff you don’t need. Another advantage of streaming in terms of bandwidth consumption comes from compression and/or lower resolutions. Most sites stream low-res versions of their stuff but don’t offer the same for downloads. Sure, the quality of a low-res version is lower, but if data usage is your top concern, and you are fine with smaller/blurrier videos, streaming is your better choice.
Compression, such as H.264, also helps to reduce file size, not necessarily at the expense of quality. Compression removes redundant data which leads to a significant decrease of the file size. Well, sometimes the codec removes useful data it wrongfully classifies as redundant, but as I already mentioned, if bandwidth is more important to you than quality, this won’t bother you much. Streaming might consume less bandwidth, but it requires a fast connection. If it isn’t fast enough, get prepared for chopped video/audio with huge interruptions between the scenes. So, after all, does streaming use more data than downloading? The short answer is that with comparable quality of the file and without compression, they use more or less the same amount of data. For one-time viewing of a compressed file, or if you are fine with low-res, use streaming to save bandwidth (and time). The same applies to audio, but since audio files are usually smaller than video files, with them data usage is less of an issue.
