The reason why it is not completely working is because Showdown uses two different types of moveset codes. For any wrestler that appears in a 1st attire slot, it uses the same method that is demonstrated in the video. Normally, each attire in a wrestler slot shares the same moveset. However, Showdown has a special feature where each attire in a wrestler slot is able to have a different moveset. This is done using WldFb's attire specific moveset converter, which can be found here:
https://www.tapatalk.com/groups/wldfbarchiveforum/attire-specific-moveset-converter-t6.html (2nd to last post). You will need that tool as well to replace Seth's moveset because he is located in attire 2.
The code for Seth is made up of 12 parts because his original moveset was converted using that tool to work for just attire 2. So, in order to change this longer moveset code, you will need to sort of reverse engineer what his code originally was before it was converted. This can be done using the two tools created by WaylonMercysHands found here:
http://nextwave-64.online/forum/index.php?topic=17115.msg128756#msg128756. You might need Java Runtime Environment in order to run these tools.
Once you have these two tools downloaded, you need to follow the following steps:
1. Since Seth Rollins replaces the Perry Saturn wrestler slot, make a copy of the default moveset file for Saturn that came with the attire tool and name it default.txt.
2. Create a file called shortened.txt and paste the moveset code listed for Randy Orton (since he is the 1st attire) into it.
3. Follow WaylonMercysHands's tutorial for the Shortened To Full Converter tool to convert Orton's current/compressed moveset into the full version of his moveset.
4. Follow WaylonMercysHands's tutorial for the 4-in-1 Moveset Reverse Converter tool to convert Orton's full moveset code and Seth's attire specific moveset code into Seth's full moveset code.
5. Once you have done this, the code that you have will be in a form that WldFb's Moveset Editor version 3.0 will accept. So, paste the current code into the tool and make any changes you want to create a new full moveset code.
6. Use WldFb's attire specific moveset converter on Orton's full moveset code and Seth's full moveset code to generate Seth's attire specific moveset code.
7. Replace Seth's moveset cheats in Showdown with the new codes created by the tool.
Hope this is able to help.