I am trying to take a 90 second narrated 145 MB video that I took into a compressed form so that I can send it out by email using my yahoo email account. Yahoo has a 25 MB maximum size.  What is the best software to use that will keep the original video quality?

Handbrake is good to transcode video and free.

Upload for free using:
Wetransfer.com
pcloud.com

All this allows you to transfer up to 2 Gb file. All is free, no payments needed.

Much appreciated.  I found skypixel as well that allows me to upload a video and it creates a link that I can email.

Hello there AirAl. Thank you for reaching out and for these information you have shared with us. I hope that you will get the best recommendation from our fellow DJI co pilot on what is the best 3rd party software they are using and with regards to this matter. Have a safe and a happy flying always.

TunesKit AceMovi can help you compress your video file smaller within several clicks.