Some times we want to add as many tags as we want on youtube video,But when we are tagging the video if we are just tagging 5 to 10 tags we will not face any Error like Your settings could not be saved: Invalid tags,I make a research on it and spend a few time on it.I read on yahoo answer like some people are saying that we can not add more then 24 tags according to the answers i found on yahoo. Its means that we can not add more then 24 tags with our youtube video,if we want to add More tags, we might find a error saying that Your settings could not be saved: Invalid tags.
But what i Found is that there is no As such limitation on the No of tags .you could add multiple tag up to 100 tag at the same time with your video even if tags are same for example aa,aa.aa
We Can tag 2 similar tags as well like 1st tag is aa, second tag can be aa, as well there is no problem with the similar tags .According to my analysis we could make the tag with up to 500 characters with spaces,Regard less of no of tags.SO We can make 1 tag with up t0 499 characters (with space) in it. As we all know that we can not make a Tag like using Just 1 character For example A,E,R,T, youtube will not accept the tag which consist of 1 character in it.It has to be 2 characters for a Valid tag.So we have up to 499 Characters to make the tags so We can Say if we divide 500/2=250 we could make up to 250 tags with one video if they all consist on 2 characters. So you can make 1 tag with up to 499 characters or you can divide it in multiple character .The smaller the size of the tag in character the more multiple tags you can make.
This is what i found on my research,if you like it please like and share .If you know better please explain in comments thank you.
I have also explained all that in the term of a video .which is given below you could see that as well