MP4Tools is intended to process video. In this regard, the tool can convert MKV, AVI and OGM files into MP4. Likewise, it can edit videos with common operations, like trimming, splitting and merging.
Its interface is quite similar to those of other apps of the same family, like AVITools and MKVTools. This means that, if you are familiar with them, you will have no problems to use it. However, it is my opinion that its interface is somewhat messy, which makes the tool unnecessarily difficult to use.
The application supports two main modes: editing and converting. When editing, you should always start by importing the desired files. Fortunately, there are user presets with contain your preferences as to an intended playback device, media type, subtitle mode, etc. Yet, it is a shame that you will have very limited visual feedback when you are performing such operations as trimming and splitting. If you are editing movies, it is great to add such metadata as cast, director, year and screenwriters, which facilitate their indexing.
In converting mode, it is necessary to load the files. Then, you can make a selection of the audio and video tracks you want to extract, in case there are multiple ones available. Moreover, you can add and edit subtitles. Finally, you may proceed to convert.
All in all, MP4Tools can process video files with reasonable speed and accuracy. It is a tool I recommend in spite of my view that its interface needs redesigning to make it more intuitive. Luckily, the product can be used for free except that it will show occasional nag screens.