I assume you are not aware that DISH invited TiVo in to show off there wares under the premise the two would work towards a partnership. Then DISH reverse engineered one of their devices (that TiVo loaned them) and looked at the source code; afterward, DISH decided they didn't need TiVo and could develop their own in-house DVR. So given those details, to me it sure seems that DISH stole TiVo's intellectual property -- and courts seem to agree.
Like Greg said, DISH was late to the DVR partly and not developing their DVR technology at the same time as TiVo (and ReplyTV) were.
And this is fact or just accepted assumption because the prototype ended up "missing"?