How to deal with large raw uncompressed video files

How you do this depends a lot on whether you want to keep cataloging the same files in Lightroom Classic, like if you organized them in collections. If preserving organization, metadata, or edits is important, then it would be ideal to convert them to copies with the same filename so Lightroom Classic doesn’t lose track of them, because if it does, you have to manually relink them. If you only break the links of 20 video files, maybe that’s not so bad. But if the filenames of 400 files change, you’ll have to manually relink them 400 times.

Unfortunately, if the only way to save a lot of space is to use a different file format, then there is no way to do this without breaking links, because the filename extensions will have to change. Also unfortunately, Lightroom Classic has no way to automatically bulk re-link to identical filenames of different filename extensions. (Maybe there is a plug-in that can?) So to achieve the stated goal and keep them in Lightroom Classic, manually re-linking a lot of files might be unavoidable.

If you want to avoid all of that hassle because it might consume many hours of your time (not just relinking, but also the time required to transcode the video files), a simpler alternative is to leave things as they are, buy a larger storage volume, and move everything to that.

How can I go through the catalog and convert/update all uncompressed videos to the latest compressed video format (H.264)?

By @jranaudo

The latest compressed video format is not H.264. It’s H.265/HEVC, which is said to need only half the data to maintain the same level of quality as H.264. H.265 has been in use for a while; if a recent iPhone is set to High Efficiency (which I think is the default today), it’s recording in H.265/HEVC.

If you still want to convert, Handbrake is a good choice, and if your Creative Cloud subscription includes Adobe Media Encoder (used with Adobe video apps) that would do it too. Both offer many more video export options which are also more up-to-date than the extremely limited options for video in the Export dialog box in Lightroom Classic. Also in both, you can create an export preset, dump a bunch of video files into the queue, click the Start button and walk away.

Alternatively, you could use the free Handbrake app to do very high-quality conversion to H.265 (HEVC), the latest format that is now well-supported by most platforms.

You know you can export the videos as H264? This is from the export dialog:

Videos are only recorded and don't take up space in LR. They take up space on your hard drive, so just get a bigger hard drive?

Lrc is not a video editor. You will need a different program for that.