Using a pre-built video transcoding solution

A lot of cloud providers, particularly CDN providers, offer some form of video streaming service, that takes care of transcoding and serving videos for you. These can seem like easy, convenient solutions - which to be fair, they are - but they have specific advantages and disadvantages, and you should consider carefully if they suit your use case.

Advantages

Ease of deployment

Since you don't have to do any development, getting your site to support user uploaded videos (or other video content) is a lot faster and easier using a pre-built solution. 

Low likelihood of bugs

When making your own transcoding solution, there's always the risk of having weird bugs here and there. The pre-built solutions are generally designed by large teams, and have many different customers, so they're going to have been rigorously tested and will be unlikely to give you much trouble in terms of bugs or errors.

Disadvantages

Lack of configuration choices and control, lower quality

Depending on your use case, a pre-built video transcoding solution might not have the options you need it to have (for instance, it might only support a certain set of resolutions and not any others).

In addition, many prebuilt solutions don't give you much, if any, control over how videos are transcoded. This can be problematic if you need videos to be to a particular quality standard, or you want them to be small in filesize but not low in quality, neither of which prebuilt solutions are generally aimed at.

Can be more costly in the long run

In theory, prebuilt solutions seem cheap; they don't need you to develop your own solution, so you don't have to pay a developer. On top of that, they often provide transcoding as part of the price, compared to doing it yourself where dedicated transcoding services cost money for each video you transcode.

The downside of this is that if you have a use case where videos are going to be uploaded once, but viewed a very large number of times, the primary cost you will incur may not be from transcoding the video but from serving it to large numbers of users, and so being able to have more control over exactly how the video is encoded is very important there. 

The result is that you'll end up paying more in CDN costs than you would have paid in transcoding fees, and for lower quality video as well.