When it comes to video song editing, there are a lot of different apps out there. It really depends on your needs, budget and the type of editing you need to do. For basic editing, most video editing apps should be just fine, but if you are looking for more professional level editing, there are a few great options you could consider.
One of the best apps for video song editing is Adobe Premiere Pro. Premier Pro provides a very powerful set of tools for an array of editing tasks, including editing songs for videos. It is not a free app, however, so if you are looking for something free to use, you may want to try a few other options. Another great option is Davinci Resolve, which is a free, professional grade video editing suite. It's quite a bit more complicated than Premiere Pro, but it provides a great set of tools for editing songs in videos.
If you are on a tight budget, or just prefer something simpler to use, there are a few good alternatives to these professional grade applications. iMovie is a popular (and free) video editing app available on Apple devices. It doesn't feature the same level of features as Premier Pro or Davinci Resolve, but it's easy to use and offers everything you need for basic video editing. For Android users, Viva Video is a great option for song editing. It's user friendly and feature-rich, and offers a variety of options for video editing.
All of these apps are great for song editing and should provide you with all the tools you need to get the job done. Whichever app you decide to use, make sure to spend some time familiarizing yourself with the features so you can achieve the optimal results for your video.