Thanks fiddlinsteudel,
If you notice, when he plays louder his body position changes. This is a good way to both feel and convey dynamics. Generally players become more erect (violin higher) when playing louder and limper (violin lower) when playing softer. The direction of the violin often moves forward on a crescendo and back on a diminuendo. Everyone is different and does things differently but these are common general movements.
Generally, but not absolute, you will be pretty safe to make crescendos on climbing scales, or notes. Higher notes louder, climactic. Of course the opposite is possible too but it all depends on the phrase (the sentence) in the music. See the music as a story, the sections as paragraphs and the 2, 4, 8 measure phrases (can be more, depends on the time signature and the composition) as sentences. If you are saying the same thing twice, you may want to say it louder the second time or echo the first..... You might want to emphasize something beautiful or out of the ordinary.....
These are just basic figure it out yourself tips and I'm glad the topic was raised. Music without phrasing, dynamics, and articulations is like an image without light, color or contrast. It can still be nice but add the color and you get something special.