NBR Takes a Long Time to Buffer and the Downloaded File will not Play

NBR takes a long time to buffer and the downloaded file will not play - Error: "File Format Is Not Valid".

Network Based Recording (NBR) take a long time to buffer.
I cannot play the downloaded ARF recording.

How do I split a large NBR file into smaller recordings?

MP4 Recordings Default in Webex Meetings 40.10

In the upcoming October (40.10) update, all-new recordings in Webex Meetings will be stored in MP4 format, either in the cloud or locally as selected at the site or host level, with a video-centric experience. By standardizing the recording format, you'll have a wider choice of playback tools, better security, and a more effortless collaboration experience even after your meetings. Existing ARF and WRF recordings can still be downloaded or played at the Webex site. For more information regarding video-centric recording, go to Video-Centric Network-Based MP4 Recordings in Webex Meetings and Webex Events.

Cause:

Recordings that are larger than 4GB will take a long time to buffer and cannot be downloaded.

Solution:

Workaround: Split the ARF file into 2 or more files and then convert them.

Follow the steps below to split the ARF file in Classic View:

Log into your Webex site. (Example: SITENAME.Webex.com)
Click on My Webex in the top navigation bar.
Click on the My Recordings tab.
Select the Recording you want to split.
Click the Modify button.
Add the text Part1 to the end of the Topic.
Within the Playback control box, select Partial playback.
Look at your total recording time (Example 2 hours) and make the end time to be half of the total time (Example: 1:00:00).
Select Save.
On the right side of the page, Select 'If you want to download the recording, click here.'
Download the recording.
You should now be able to open the recording and convert it to MP4.
Repeat steps 2 - 12, but for step 7, Topic add the text Part2, then for Step 9 have the start time begin where you left off in Part 1 (Example: 1:00:01).
Once you have downloaded the (2) smaller recording files and converted them to MP4, you can use a 3rd party MP4 joiner to combine the files back into one file.