Is the MacBook Air M3 suitable for video editing and law school?

I feel it is safe to say that any Apple product available today can handle the workload you are defining. But you have polar opposite objectives: Law school and video editing. The law school part can be handled by any computer over the last decade to a decade and a half because the machine needs to be as fast as your hands can type letters. This is something the computing industry mastered decades ago. For your law studies you will be reading and writing (typing). You will not be transcoding data, compiling code, or other processor intensive tasks. And your law studies will likely result in relatively small data sets when compared to your video work.

Ah, the video work. This is a loaded question as "video" can mean a lot of different things to a lot of different people. I have one "video" customer that uses her iPhone and produces how to videos for YouTube distribution. I have another "video" customer that strapped a Red camera to a drone and flies it over the ocean. The footage is then processed and converted to digital wave simulations in Cinema 4D or extracted stills are pulled out into huge Photoshop projects. They are both doing "video and photo" editing but they both have drastically different needs regarding computers and storage.

You should consider your workflow, specifically storage needs, to make sure you are configuring the device to fit your needs today and at least three years from now. The faster processors are best for professionals doing lots of batch processing or background tasks.

Consider your workflow as a linear bar chart. You start on the left with creating content. In your case, capturing video. What format(s) do you capture in? What camera are you using? How long are your clips? How much storage do they consume? Do you use external media for the projects? Next, move along the line to editing. At this point, are you doing render proxies? Are you leaving media at source (if using external drives) or copying to project folders? This all has impact on your built in storage. Do you work on multiple projects at once? How long are your projects? The next step is output. After you finish the project, what is your output format(s)? How long are you storing the projects? What is your retention policy? Beyond that there is long term archive of the projects. I will assume you don't plan to delete everything once you post the final. That being the case, do you need everything kept local or do you have to offload to external/cloud storage locations.

The key here is that you understand your workflow and your storage needs. This can help spec an appropriate machine that will work for you today and years from now.

Oh, and since I am a monitor snob, also consider your screen size. A 13" Air is light and fast but a little cramped for all the palettes and timelines of working on video.

Hope this is helpful. It is your workflow. Do the math. Make an informed configuration decision.