backup - Refresh SD Cards for Long term storage for video files?

I have a large collection of video files most of them in mp4 format. I currently store them in SD Cards. Once I finish filling a SD Card I lock it and never use it again unless I need to read the files.

My intention is to be able to read those files in 30 years. I have been researching and it appears that even If I don’t use the card and properly store it some data degradation will occur. Is that right?
I also tried to compare it with other storage Medias but most of the information I have found online don’t come from “official” sources.

There is any way of refreshing the charge in SD cards without copying in and out the information manually or should I replace the cards every five years?

Answer

The question is two years old but still relevant. I've had same problem on archiving an huge image archive. Will answer to the question marked in bold.

No, you don't have to replace the SD cards. You only need to refresh them just plugging them in a device capable of read/write them, and use any tool that reads sectors on disk and rewrite them unchanged. This procedure may be done just once every 4 years, that is shorter than the average life span of stored bits. Manifacturer's quality applies.

As Hennes pointed up, still today year 2016, the best media for long term and untouched storage is magnetic tape. But it suffers from being sensitive to magnetic fields and the fast obsolescence of media readers: after 20 years it may be possible you haven't a working tape reader for your data.

De facto, the actual best long term storage are quality SD cards plus the 4 year refresh. This is good for sensitive/military/strategic archives, because every 4 years you can assess the status-quo of technology and if you decide to move the archival media to another thing, you have commercially available both media readers/writers and transfer data to the new medium without the pain of find any reader for the old one.

Another good practice, is have always at disposal two (or more, depends how much important the data is) copies of the archive, stored in different places, so you can recover data being destroyed by other means than media degrade.

I will not support the use of mechanical drives for long term storage because it is proven a sitting HDD may fail to start again if stored more than one year untouched, on the average. It may fail even sooner.