Add video download button

Fixes #263

public/fonts/fontello.svg

@@ -6,6 +6,8 @@
 <font id="fontello" horiz-adv-x="1000" >
 <font-face font-family="fontello" font-weight="400" font-stretch="normal" units-per-em="1000" ascent="850" descent="-150" />
 <missing-glyph horiz-adv-x="1000" />
+<glyph glyph-name="group" unicode="&#xe0c3;" d="M0 106l0 134q0 26 18 32l171 80q-66 39-68 131 0 56 35 103 37 41 90 43 31 0 63-19-49-125 23-237-12-11-25-19l-114-55q-48-23-52-84l0-143-114 0q-25 0-27 34z m193-59l0 168q0 27 22 37l152 70 57 28q-37 23-60 66t-22 94q0 76 46 130t110 54 109-54 45-130q0-105-78-158l61-30 146-70q24-10 24-37l0-168q-2-37-37-41l-541 0q-14 2-24 14t-10 27z m473 330q68 106 22 231 31 19 66 21 49 0 90-43 35-41 35-103 0-82-65-131l168-80q18-10 18-32l0-134q0-32-27-34l-118 0 0 143q0 57-50 84l-110 53q-15 8-29 25z" horiz-adv-x="1000" />
+
 <glyph glyph-name="views" unicode="&#xe800;" d="M180 516l0-538-180 0 0 538 180 0z m250-138l0-400-180 0 0 400 180 0z m250 344l0-744-180 0 0 744 180 0z" horiz-adv-x="680" />
 
 <glyph glyph-name="heart" unicode="&#xe801;" d="M790 644q70-64 70-156t-70-158l-360-330-360 330q-70 66-70 158t70 156q62 58 151 58t153-58l56-52 58 52q62 58 150 58t152-58z" horiz-adv-x="860" />
@@ -14,8 +16,6 @@
 
 <glyph glyph-name="comment" unicode="&#xe803;" d="M1000 350q0-97-67-179t-182-130-251-48q-39 0-81 4-110-97-257-135-27-8-63-12-10-1-17 5t-10 16v1q-2 2 0 6t1 6 2 5l4 5t4 5 4 5q4 5 17 19t20 22 17 22 18 28 15 33 15 42q-88 50-138 123t-51 157q0 73 40 139t106 114 160 76 194 28q136 0 251-48t182-130 67-179z" horiz-adv-x="1000" />
 
-<glyph glyph-name="group" unicode="&#xe804;" d="M0 106l0 134q0 26 18 32l171 80q-66 39-68 131 0 56 35 103 37 41 90 43 31 0 63-19-49-125 23-237-12-11-25-19l-114-55q-48-23-52-84l0-143-114 0q-25 0-27 34z m193-59l0 168q0 27 22 37l152 70 57 28q-37 23-60 66t-22 94q0 76 46 130t110 54 109-54 45-130q0-105-78-158l61-30 146-70q24-10 24-37l0-168q-2-37-37-41l-541 0q-14 2-24 14t-10 27z m473 330q68 106 22 231 31 19 66 21 49 0 90-43 35-41 35-103 0-82-65-131l168-80q18-10 18-32l0-134q0-32-27-34l-118 0 0 143q0 57-50 84l-110 53q-15 8-29 25z" horiz-adv-x="1000" />
-
 <glyph glyph-name="play" unicode="&#xe805;" d="M772 333l-741-412q-13-7-22-2t-9 20v822q0 14 9 20t22-2l741-412q13-7 13-17t-13-17z" horiz-adv-x="785.7" />
 
 <glyph glyph-name="link" unicode="&#xe806;" d="M294 116q14 14 34 14t36-14q32-34 0-70l-42-40q-56-56-132-56-78 0-134 56t-56 132q0 78 56 134l148 148q70 68 144 77t128-43q16-16 16-36t-16-36q-36-32-70 0-50 48-132-34l-148-146q-26-26-26-64t26-62q26-26 63-26t63 26z m450 574q56-56 56-132 0-78-56-134l-158-158q-74-72-150-72-62 0-112 50-14 14-14 34t14 36q14 14 35 14t35-14q50-48 122 24l158 156q28 28 28 64 0 38-28 62-24 26-56 31t-60-21l-50-50q-16-14-36-14t-34 14q-34 34 0 70l50 50q54 54 127 51t129-61z" horiz-adv-x="800" />
@@ -44,6 +44,8 @@
 
 <glyph glyph-name="attention-circled" unicode="&#xe812;" d="M429 779q116 0 215-58t156-156 57-215-57-215-156-156-215-58-216 58-155 156-58 215 58 215 155 156 216 58z m71-696v106q0 8-5 13t-12 5h-107q-8 0-13-5t-6-13v-106q0-8 6-13t13-6h107q7 0 12 6t5 13z m-1 192l10 346q0 7-6 10-5 5-13 5h-123q-8 0-13-5-6-3-6-10l10-346q0-6 5-10t14-4h103q8 0 13 4t6 10z" horiz-adv-x="857.1" />
 
+<glyph glyph-name="download-alt" unicode="&#xe813;" d="M0-150l0 135 1000 0 0-135-1000 0z m88 586l228 0 0 414 370 0 0-414 228 0-414-385z" horiz-adv-x="1000" />
+
 <glyph glyph-name="circle" unicode="&#xf111;" d="M857 350q0-117-57-215t-156-156-215-58-216 58-155 156-58 215 58 215 155 156 216 58 215-58 156-156 57-215z" horiz-adv-x="857.1" />
 
 <glyph glyph-name="info" unicode="&#xf128;" d="M393 149v-134q0-9-7-15t-15-7h-134q-9 0-16 7t-7 15v134q0 9 7 16t16 6h134q9 0 15-6t7-16z m176 335q0-30-8-56t-20-43-31-33-32-25-34-19q-23-13-38-37t-15-37q0-10-7-18t-16-9h-134q-8 0-14 11t-6 20v26q0 46 37 87t79 60q33 16 47 32t14 42q0 24-26 41t-60 18q-36 0-60-16-20-14-60-64-7-9-17-9-7 0-14 4l-91 70q-8 6-9 14t3 16q89 148 259 148 45 0 90-17t81-46 59-72 23-88z" horiz-adv-x="571.4" />