You need VirtualDubMod which you can find here.

1) Open VirtualDubMod to load the Video
"File" > "Open video file..." > "Video - englisch.avi" > "Open"

2) You may recieve a message if you want to rewirte the header – You should choose „No“

3) Now the Video is loaded
Open the "Streams" > "Stream list"

4) Here you can see all the soundtracks of this video. From Now you have 2 different Possilbilities :

Possibillity A:
To delete the englisch soundtrack and to add the germen one.

• Result would be a video  with just a german soundtrack

The Size of the video won’t change much.
Example : "350MB Video eng." - "40MB eng. Tonspur" + "40MB deu. Tonspur" = "350MB Video deu."

Possibillity B:
To keep the english soundtrack and to add the german one.

• Result would be a dual-language Video . The Video would be larger cause of the amount of the second soundtrack.
  Example: "350MB Video eng." + "40MB deu. Tonspur" = "390MB Video eng. & deu."

 

 

Possibillity A:
( delete the english soundtrack and add the german one )

First disable the english soundtrack.



 

Now you can add the german soundtrack.





 

The Soundtrack is loading...



 

You may recieve a message if you want to rewirte the header – You should choose „No“ (This just appears if the soundtrack contains a VBR!)



 

The Soundtrack is loaded – Choose „OK“.



 

Now you just have to save the Video.
"File" > "Save as..." > "Video NAME.avi" > "Direct stream copy" > "Save"



 

IMPORTANT you should choose "Direct stream copy". Otherwise the Video will be new encoded (wich takes a lot of  Time). With "Direct stream copy" it just takes some minutes!



 

After the next window disappears you are ready with the Video!



 

 

Possibillity B:
( To keep the english soundtrack and to add the german one. )

Just add the german soundtrack and choose „OK“.



 



 

The Soundtrack is loading...



 

You may recieve a message if you want to rewirte the header – You should choose „No“ (This just appears if the soundtrack contains a VBR!)



 

The Soundtrack is now loaded , but added as No.2. In this case you had to chosse it in your player  - to avoid this just mark the soundtrack and push „Move Up“.




 

Now the Soundtrack is placed on No.1.

Choose “OK”.



 

Now you just have to save the Video.
"File" > "Save as..." > "Video NAME.avi" > "Direct stream copy" > "Save"



 

IMPORTANT you should choose "Direct stream copy". Otherwise the Video will be new encoded (wich takes a lot of  Time). With "Direct stream copy" it just takes some minutes!



 

After the next window disappears you are ready with the Video!