Here is the former explanation about how the tapes were erased from Reuters in 2009.
WASHINGTON (Reuters) – The original recordings of the first humans landing on the moon 40 years ago were erased and re-used, but newly restored copies of the original broadcast look even better, NASA officials said on Thursday.
NASA released the first glimpses of a complete digital make-over of the original landing footage that clarifies the blurry and grainy images of Neil Armstrong and Buzz Aldrin walking on the surface of the moon.
The full set of recordings, being cleaned up by Burbank, California-based Lowry Digital, will be released in September. The preview is available at www.nasa.gov.
NASA admitted in 2006 that no one could find the original video recordings of the July 20, 1969, landing.