当然，即使对于在线视频，我们也并不清楚如此细分是否真的具有经济价值。
Of course, it' not yet clear that such niches will work economically, even online.
即使广告客户会评估这些新设想，Youtube和其他的在线视频分享网站仍然有其他的一些困难需要面对。
Even as advertisers evaluate these new ideas, however, YouTube and the other video-sharing sites face other difficulties.
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