try cleaning/purging the media cache from the cache preferences in ae.
if that doesn't help, you might just convert the media using mpeg streamclip (free & multiplatform, just search for it) or another utility or export from an nle as a different format & codec. media like hdv doesn't play nice with after effects anyway, so if you convert it you may be better off. try converting to quicktime lossless mov, quicktime photo-jpeg, apple's prores (need fcp) or avid's dnxhd (free from avid, uses quicktime format).
Instead of converting, try just re-wrapping. Is faster and you'll lose no quality. Try CLIPWRAP software.. It will rerap m2t footage to mov footage (keeping m2t format inside). It might be easier for AfterFX to work with it.
rewrapping is usually preferable, and it may correct that error, but if the footage is still encoded by a codec that uses inter-frame compression (or temporal compression, b-frame/p-frame compression), like hdv, mpeg-2, h.264, etc., ae will still not work as well with it and it can lead to general flakey behavior in ae.