For video size, encoder and Bit Rate of video are the most important points. In broad terms, the video size is determined by bit rate. Under the same resolution, the higher bit rate the video possesses, the bigger the video size is.

After the video compression, the size of source file and output file may differ widely due to the changes of encoder and bit rates. However, it is not wise to directly make changes by your own efforts if you're not familiar with it. You may seek help for some software like reduce video file size software, shrink video converter or video compression software.

Here you can download the professional “reduce video file size software - HD Video Converter Factory Pro” right now to have a try and you’ll find it’s usable.

Method 1: Shrink Video Size with H.265 Encoder

Method 2: Reduce Video Size with Build-in Advanced Compressor Bar

Method 3: Cut Off Unwanted Part

Nice tips! Thanks for sharing

I used the recommended software to resize the video and it converted it to an MP4 file. Now it won't play on Quicktime. When I select the MOV file and run the software it doesn't resize it. Any suggestions?

I used the recommended software to resize the video and it converted it to an MP4 file. Now it won't play on Quicktime. When I select the MOV file and run the software it doesn't resize it. Any suggestions?

rick_anderson＼@f Posted at 7-3 15:06
I used the recommended software to resize the video and it converted it to an MP4 file. Now it won't play on Quicktime. When I select the MOV file and run the software it doesn't resize it. Any suggestions?

Play the video on something other than Quicktime.
It's not the only video viewing software.

Can I reduce a 100+ MB file to a 25 MB file so that I can email my video without losing quality?  Does it allow you to choose the compressed size you want?

AirAl Posted at 1-19 06:13
Can I reduce a 100+ MB file to a 25 MB file so that I can email my video without losing quality?  Does it allow you to choose the compressed size you want?

It's not hard to compress 100+ to 25MB. You can do it in different ways:
1. convert the video to hevc,
2. lower the resolutions, will result in quality loss
3. zip the file
4. edit the file, like cut unwanted parts in something like iMovie, which allows you to select the output size
More details here https://bit.ly/3tUYuBr