If you are referring to learning the postures or asanas of yoga in a general sense, perhaps you can, though I have to say that, for a beginner, there’s no substitute for a teacher’s eye. The video is a one dimensional teaching medium which doesn’t cater to the unique body and energy patterns which you would have. The specific hands-on adjustments and personal pointers which can really open you to the knowledge of your body require an experienced and knowledgeable teacher with whom you have a good rapport. However in the absence of one, you can start off with the instructional videos of reputed teachers and schools.

Also, yoga is not just about stretching your legs, body and shoulders. We have to see stretching as stretching and not as yoga. Though the asanas superficially give the impression that they are stretches, the Sanskrit word asana derives its root from ‘as’ which means ‘abiding’. This, among other things, means that asana is a tool by which we cultivate the quality of attentive steadiness or the ability for sustained abiding in a chosen object of focus, instead of the usual scattering, vacillating tendency of mind.

However, if you only learn exclusively from videos, it is easy to get lost in a stretching mentality. When I sometimes see or overhear students in disgruntled tones comparing their postures with what they see in pictures and videos, I think they are paying more homage to Narcissus than Patanjali. This quickly brings about desires, comparisons, disappointment, arrogance etc, which in a collective sense, becomes the antithesis of yoga, which stands for a resolved, harmonious, serene state of attentive, receptive consciousness.

You need a good teacher to slowly stretch your awareness away from this kind of movement of mind, such as ‘how to become’ like that model in the video or the magazine’, and instead move you towards the ‘pure being of you’ as in this moment, which will give rise to a state of  fulfilment, peace and happiness.

So, as an answer again, videos are good as supplements but can never be substitutes for an actual yoga class.