Praise be to Allah.
What you say about it being haraam to take photographs and keep them except in cases of necessity, and it being permissible to watch TV and videos if they are free of evils, is the view of a number of scholars, including Shaykh Ibn Baaz (may Allaah have mercy on him) and the scholars of the Standing Committee for Issuing Fatwas, may Allaah preserve them.
The confusion that you mentioned was answered by Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him), who explained that pictures contained on a video tape and the like are stored in the form of electro-magnetic waves, hence they were regarded as permissible by those who do not regard photographs as permissible.
He (may Allaah have mercy on him) said: Images made by modern methods are of two types:
1 – Those that are stored in a way that does not have any tangible or visible form, as was mentioned in the case of images, such as video tapes. There is no ruling on these at all and they do not come under the prohibition at all. Hence the scholars who forbid photographs printed on paper regarded them as permissible, and said that there is nothing wrong with them. It was said: Is it permissible to film the lectures that are given in mosques? Their opinion was that this should not be done, because it may disturb those who are praying there, and it does not befit the place, and so on.
2 – Photographs that are printed on paper.
But there remains the question: if a person wants to make these permissible images, then he is subject to the five rulings according to his intention. If he intends thereby to do something haraam, then it is haraam. If he intends thereby to do something obligatory then it is obligatory. It may be obligatory to make images sometimes, especially moving images. For example, if we see someone committing a crime that is a crime against a person’s rights, such as a murder attempt and the like, and it cannot be proven except by means of a picture, then in that case taking a picture is obligatory, especially in cases where pictures could tell the full story, because the means are subject to the same rulings as the ends. If we use this image-making to prove the identity of a person lest he be accused of a crime committed by someone else, there is nothing wrong with this either, rather it is essential. But if we take a picture in order to enjoy looking at it, this is undoubtedly haraam. End quote from al-Sharh al-Mumti’ (2/197-199).
And Allaah knows best.